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 Posted: Thu Mar 29, 2007 3:25 pm
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Posted: Thu Mar 29, 2007 8:27 pm
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Posted: Thu Mar 29, 2007 9:03 pm
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Posted: Fri Mar 30, 2007 9:54 am
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Posted: Fri Mar 30, 2007 2:52 pm
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Steven Hawkings AstronomyGirl I remember learning about these a while ago. They all have their advantages. I've always liked the idea of the solar sails. They would be great for solar system missions. Ones were we have to get to the outer solar system. yea there's not as much sunlight out there, but we're just drifting along anyways. Dont' need really great speeds to get probes out there. Ion drives require to to run the engine for a year or so to get it to fast speeds solar sails of course deflect photons off the sails that push it forward, but the fuel source is the sun and in order to get it to fast speed one must get as close as possible, risky. Flying sucuers like the ones in the movies at this time are not a stable platform unless you add aircraft features like a fighter cockpit and rudders and shape it in more of a oval shape, but it still retains the title still.
"I don't believe it would take a year. But really, that long!?! That maybe how fasts it accelerates now ah days"... |
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Posted: Sun Apr 01, 2007 1:19 pm
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Posted: Sun Apr 01, 2007 5:33 pm
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Posted: Mon Apr 02, 2007 10:12 pm
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Posted: Mon Apr 02, 2007 10:15 pm
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AstronomyGirl Raven Yun Harnessing antimatter would be a silly thing to do! It would cost far, far, FAR too much in terms of human life, property damage, and the countless quadrillions of dollars/euros/etc. and, even if we were able to harness it after that, then it would still be too unstable to be of any great use. Too easy to get screwed with and end up costing hundreds or even thousands of lives. A better way? Harness wormholes on an atomic-sized scale to draw in power from neutron stars and other such valuable power sources. Much safer, and much, much more efficient if it was possible. eh... I don't think either are very safe. Messing around with anything that is only seen in particle accelerators or currently theoretical is very dangerous. And antimatter is fine... as long as it doesn't interact with real matter, and then in only distroys one for one. I don't see how antimatter would be so distrctive. What's your source on that?
In 1995 CERN announced that it had successfully created nine antihydrogen atoms by implementing the SLAC/Fermilab concept during the PS210 experiment. The experiment was performed using the Low Energy Antiproton Ring (LEAR), and was led by Walter Oelert and Mario Macri. Fermilab soon confirmed the CERN findings by producing approximately 100 antihydrogen atoms at their facilities.
The antihydrogen atoms created during PS210, and subsequent experiments (at both CERN and Fermilab) were extremely energetic ("hot") and were not well suited to study. To resolve this hurdle, and to gain a better understanding of antihydrogen, two collaborations were formed in the late 1990s — ATHENA and ATRAP. The primary goal of these collaborations is the creation of less energetic ("cold") antihydrogen, better suited to study.
In 1999 CERN activated the Antiproton Decelerator, a device capable of decelerating antiprotons from 3.5 GeV to 5.3 MeV — still too "hot" to produce study-effective antihydrogen, but a huge leap forward. In late 2002 the ATHENA project announced that they had created the world's first "cold" antihydrogen. The antiprotons used in the experiment were cooled sufficiently by decelerating them (using the Antiproton Decelerator), passing them through a thin sheet of foil, and finally capturing them in a Penning trap. The antiprotons also underwent stochastic cooling at several stages during the process.
The ATHENA team's antiproton cooling process is effective, but highly inefficient. Approximately 25 million antiprotons leave the Antiproton Decelerator; roughly 10 thousand make it to the Penning trap. In early 2004 ATHENA researchers released data on a new method of creating low-energy antihydrogen. The technique involves slowing antiprotons using the Antiproton Decelerator, and injecting them into a Penning trap (specifically a Penning-Malmberg trap). Once trapped the antiprotons are mixed with electrons that have been cooled to an energy potential significantly less than the antiprotons; the resulting Coulomb collisions cool the antiprotons while warming the electrons until the particles reach an equilibrium of approximately 4 K.
While the antiprotons are being cooled in the first trap, a small cloud of positron plasma is injected into a second trap (the mixing trap). Exciting the resonance of the mixing trap’s confinement fields can control the temperature of the positron plasma; but the procedure is more effective when the plasma is in thermal equilibrium with the trap’s environment. The positron plasma cloud is generated in a positron accumulator prior to injection; the source of the positrons is usually radioactive sodium.
Once the antiprotons are sufficiently cooled, the antiproton-electron mixture is transferred into the mixing trap (containing the positrons). The electrons are subsequently removed by a series of fast pulses in the mixing trap's electrical field. When the antiprotons reach the positron plasma further Coulomb collisions occur, resulting in further cooling of the antiprotons. When the positrons and antiprotons approach thermal equilibrium antihydrogen atoms begin to form. Being electrically neutral the antihydrogen atoms are not affected by the trap and can leave the confinement fields.
Using this method ATHENA researchers predict they will be able to create up to 100 antihydrogen atoms per operational second. ATHENA and ATRAP are now seeking to further cool the antihydrogen atoms by subjecting them to an inhomogeneous field. While antihydrogen atoms are electrically neutral, their spin produces magnetic moments. These magnetic moments vary depending on the spin direction of the atom, and can be deflected by inhomogeneous fields regardless of electrical charge.
The biggest limiting factor in the production of antimatter is the availability of antiprotons. Recent data released by CERN states that when fully operational their facilities are capable of producing 107 antiprotons per second. Assuming an optimal conversion of antiprotons to antihydrogen, it would take two billion years to produce 1 gram of antihydrogen. Another limiting factor to antimatter production is storage. As stated above there is no known way to effectively store antihydrogen. The ATHENA project has managed to keep antihydrogen atoms from annihilation for tens of seconds — just enough time to briefly study their behaviour.
According to an article on the website of the CERN laboratories, which produces antimatter on a regular basis, "If we could assemble all the antimatter we've ever made at CERN and annihilate it with matter, we would have enough energy to light a single electric light bulb for a few minutes." [1]
[edit] Naturally occurring production
Antiparticles are created everywhere in the universe where high-energy particle collisions take place. High-energy cosmic rays impacting Earth's atmosphere (or any other matter in the solar system) produce minute quantities of antimatter in the resulting particle jets, which are immediately annihilated by contact with nearby matter. It may similarly be produced in regions like the center of the Milky Way Galaxy and other galaxies, where very energetic celestial events occur (principally the interaction of relativistic jets with the interstellar medium). The presence of the resulting antimatter is detected by the gamma rays produced when it annihilates with nearby matter.
Antiparticles are also produced in any environment with a sufficiently high temperature (mean particle energy greater than the pair production threshold). During the period of baryogenesis, when the universe was extremely hot and dense, matter and antimatter were continually produced and annihilated. The presence of remaining matter, and absence of detection of remaining antimatter,[1] is attributed to violation of the CP-symmetry relating matter and antimatter. The exact mechanism of this violation during baryogenesis remains a mystery.
Positrons are also produced from the radioactive decay of nucleides such as carbon-11, nitrogen-13, oxygen-15, fluorine-18, and iodine-121
[edit] Notation
One way to denote an antiparticle is by adding a bar (or macron) over the particle's symbol. For example, the proton and antiproton are denoted as mathrm{p}, and bar{mathrm{p}}, respectively. The same rule applies if you were to address a particle by its constituent components. A proton is made up of mathrm{u},mathrm{u},mathrm{d}, quarks, so an antiproton must therefore be formed from bar{mathrm{u}}bar{mathrm{u}}bar{mathrm{d}} antiquarks. Another convention is to distinguish particles by their electric charge. Thus, the electron and positron are denoted simply as e− and e+.
[edit] Uses
[edit] Medical
Antimatter-matter reactions have practical applications in medical imaging, such as positron emission tomography (PET). In positive beta decay, a nuclide loses surplus positive charge by emitting a positron (in the same event, a proton becomes a neutron, and neutrinos are also given off). Nuclides with surplus positive charge are easily made in a cyclotron and are widely generated for medical use.
[edit] Fuel
In antimatter-matter collisions resulting in photon emission, the entire rest mass of the particles is converted to kinetic energy. The energy per unit mass is about 10 orders of magnitude greater than chemical energy, and about 2 orders of magnitude greater than nuclear energy that can be liberated today using nuclear fission or fusion. The reaction of 1 kg of antimatter with 1 kg of matter would produce 1.8×1017 J (180 petajoules) of energy (by the equation E=mc²). This is about 134 times as much energy as is obtained by nuclear fusion of the same mass of hydrogen (fusion of 1H to 4He produces about 7 MeV per nucleon, or 1.3×1015 J for 2 kg of hydrogen). This amount of energy would be released by burning 5.6 billion litres (1.5 billion US gallons) of gasoline (the combustion of one liter of gasoline in oxygen produces 3.2×107 J), or by detonating 43 million tonnes of TNT (at 4.2×106 J/kg).
Not all of that energy can be utilized by any realistic technology, because as much as 50% of energy produced in reactions between nucleons and antinucleons is carried away by neutrinos, so, for all intents and purposes, it can be considered lost.[2]
The scarcity of antimatter means that it is not readily available to be used as fuel, although it could be used in antimatter catalyzed nuclear pulse propulsion. Generating a single antiproton is immensely difficult and requires particle accelerators and vast amounts of energy—millions of times more than is released after it is annihilated with ordinary matter, due to inefficiencies in the process. Known methods of producing antimatter from energy also produce an equal amount of normal matter, so the theoretical limit is that half of the input energy is converted to antimatter. Counterbalancing this, when antimatter annihilates with ordinary matter, energy equal to twice the mass of the antimatter is liberated—so energy storage in the form of antimatter could (in theory) be 100% efficient. Antimatter production is currently very limited, but has been growing at a nearly geometric rate since the discovery of the first antiproton in 1955.[3] The current antimatter production rate is between 1 and 10 nanograms per year, and this is expected to increase to between 3 and 30 nanograms per year by 2015 or 2020 with new superconducting linear accelerator facilities at CERN and Fermilab. Some researchers claim that with current technology, it is possible to obtain antimatter for US$25 million per gram by optimizing the collision and collection parameters (given current electricity generation costs). Antimatter production costs, in mass production, are almost linearly tied in with electricity costs, so economical pure-antimatter thrust applications are unlikely to come online without the advent of such technologies as deuterium-tritium fusion power (assuming that such a power source actually would prove to be cheap). Many experts, however, dispute these claims as being far too optimistic by many orders of magnitude. They point out that in 2004; the annual production of antiprotons at CERN was several picograms at a cost of $20 million. This means to produce 1 gram of antimatter, CERN would need to spend 100 quadrillion dollars and run the antimatter factory for 100 billion years. Storage is another problem, as antiprotons are negatively charged and repel against each other, so that they cannot be concentrated in a small volume. Plasma oscillations in the charged cloud of antiprotons can cause instabilities that drive antiprotons out of the storage trap. For these reasons, to date only a few million antiprotons have been stored simultaneously in a magnetic trap, which corresponds to much less than a femtogram. Antihydrogen atoms or molecules are neutral so in principle they do not suffer the plasma problems of antiprotons described above. But cold antihydrogen is far more difficult to produce than antiprotons, and so far not a single antihydrogen atom has been trapped in a magnetic field.Quote: http://en.wikipedia.org/wiki/Antimatter |
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Posted: Mon Apr 02, 2007 10:17 pm
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Red 5 Steven Hawkings AstronomyGirl I remember learning about these a while ago. They all have their advantages. I've always liked the idea of the solar sails. They would be great for solar system missions. Ones were we have to get to the outer solar system. yea there's not as much sunlight out there, but we're just drifting along anyways. Dont' need really great speeds to get probes out there. Ion drives require to to run the engine for a year or so to get it to fast speeds solar sails of course deflect photons off the sails that push it forward, but the fuel source is the sun and in order to get it to fast speed one must get as close as possible, risky. Flying sucuers like the ones in the movies at this time are not a stable platform unless you add aircraft features like a fighter cockpit and rudders and shape it in more of a oval shape, but it still retains the title still. "I don't believe it would take a year. But really, that long!?! That maybe how fasts it accelerates now ah days"... |
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Posted: Mon Apr 02, 2007 10:58 pm
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Posted: Tue Apr 03, 2007 1:53 pm
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Kahalm I like the concept behind "ram jet" engines. Not to be confused with the airplane "ram jet". But anyway the thought is if you have a massive scoop that could collect even the extreamly small concentration of usable particals in space (mostly Hydrogen) and use them as a fuel to burn for propulsion. It would take a very long time to build, and a very long time to get up to speed, however, once it gets going it can obtain (theoretically) an speed 1/2 light or so... Theoretically... Sorry, my sources on that is print and telivision only, so I cant link... Anyway, I must note about conventional methods of propulsion. Even if you where able to make a rocket that couold approach light, You really wouldnt be able to tell many people. Since realitivity comes into play Your trip to the nearest planet (outside our solar system) and back may be only 30 years, but for everyone else it may be hundreads, or thousands... By then you'd be comming back in an antique. |
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Posted: Thu Apr 05, 2007 7:05 am
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Steven Hawkings Kahalm I like the concept behind "ram jet" engines. Not to be confused with the airplane "ram jet". But anyway the thought is if you have a massive scoop that could collect even the extreamly small concentration of usable particals in space (mostly Hydrogen) and use them as a fuel to burn for propulsion. It would take a very long time to build, and a very long time to get up to speed, however, once it gets going it can obtain (theoretically) an speed 1/2 light or so... Theoretically... Sorry, my sources on that is print and telivision only, so I cant link... Anyway, I must note about conventional methods of propulsion. Even if you where able to make a rocket that couold approach light, You really wouldnt be able to tell many people. Since realitivity comes into play Your trip to the nearest planet (outside our solar system) and back may be only 30 years, but for everyone else it may be hundreads, or thousands... By then you'd be comming back in an antique. Another method is use He-^3 on the moon as a way to get cheaply to Mars, or send the ship to Mars a year in advance while on the planet it would extract the needed material in order to get the fuel to get home. Though chemical rockets only go so far, and using hydrogen as a means is far better due to the fact that its the most common element out there, though its still a theory. I bet my money on solar sails since its a proven techolongy.
I've heard of that, im sort of doubtfull though. Not about the propulsion, but the strain on the human body in OGs that long, it could have some ill effects. |
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Posted: Thu Apr 05, 2007 9:49 pm
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Kurzon_Dax Steven Hawkings Kahalm I like the concept behind "ram jet" engines. Not to be confused with the airplane "ram jet". But anyway the thought is if you have a massive scoop that could collect even the extreamly small concentration of usable particals in space (mostly Hydrogen) and use them as a fuel to burn for propulsion. It would take a very long time to build, and a very long time to get up to speed, however, once it gets going it can obtain (theoretically) an speed 1/2 light or so... Theoretically... Sorry, my sources on that is print and telivision only, so I cant link... Anyway, I must note about conventional methods of propulsion. Even if you where able to make a rocket that couold approach light, You really wouldnt be able to tell many people. Since realitivity comes into play Your trip to the nearest planet (outside our solar system) and back may be only 30 years, but for everyone else it may be hundreads, or thousands... By then you'd be comming back in an antique. Another method is use He-^3 on the moon as a way to get cheaply to Mars, or send the ship to Mars a year in advance while on the planet it would extract the needed material in order to get the fuel to get home. Though chemical rockets only go so far, and using hydrogen as a means is far better due to the fact that its the most common element out there, though its still a theory. I bet my money on solar sails since its a proven techolongy. I've heard of that, im sort of doubtfull though. Not about the propulsion, but the strain on the human body in OGs that long, it could have some ill effects. |
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Posted: Thu Apr 19, 2007 10:56 am
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Steven Hawkings Kurzon_Dax Steven Hawkings Kahalm I like the concept behind "ram jet" engines. Not to be confused with the airplane "ram jet". But anyway the thought is if you have a massive scoop that could collect even the extreamly small concentration of usable particals in space (mostly Hydrogen) and use them as a fuel to burn for propulsion. It would take a very long time to build, and a very long time to get up to speed, however, once it gets going it can obtain (theoretically) an speed 1/2 light or so... Theoretically... Sorry, my sources on that is print and telivision only, so I cant link... Anyway, I must note about conventional methods of propulsion. Even if you where able to make a rocket that couold approach light, You really wouldnt be able to tell many people. Since realitivity comes into play Your trip to the nearest planet (outside our solar system) and back may be only 30 years, but for everyone else it may be hundreads, or thousands... By then you'd be comming back in an antique. Another method is use He-^3 on the moon as a way to get cheaply to Mars, or send the ship to Mars a year in advance while on the planet it would extract the needed material in order to get the fuel to get home. Though chemical rockets only go so far, and using hydrogen as a means is far better due to the fact that its the most common element out there, though its still a theory. I bet my money on solar sails since its a proven techolongy. I've heard of that, im sort of doubtfull though. Not about the propulsion, but the strain on the human body in OGs that long, it could have some ill effects. Well yes, that is the major concern, two years in space makes bones weak and the heart also.
It also realeses pressure on muscles, which make them longer, and they arnt in use. They could spin the ship really fast to simulate something like gravity....maybe. |
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