Slashdot Mirror
Anti-Matter Created By Laser At Livermore
zootropole alerts us to a press release issued today by Lawrence Livermore National Laboratory, announcing the production of 'billions of particles of anti-matter.' "Take a gold sample the size of the head of a push pin, shoot a laser through it, and suddenly more than 100 billion particles of anti-matter appear. The anti-matter, also known as positrons, shoots out of the target in a cone-shaped plasma 'jet.' This new ability to create a large number of positrons in a small laboratory opens the door to several fresh avenues of anti-matter research, including an understanding of the physics underlying various astrophysical phenomena such as black holes and gamma ray bursts." The press release doesn't characterize the laser used in this experiment, but it may have been this one.
Even more interesting is the possibility for mass manufacture of antimatter. By using mass-produced gold targets, you could rotate the materials in and out of the machine every few seconds, creating previously unseen amounts of antimatter.
If true, this is the 1940s all over again -- only on a larger scale. A thimbleful of antimatter would make any H-bomb look like a popgun. (...and yeah, I know we're not yet talking about anywhere near that order of magnitude. Yet.) It would certainly help with space exploration -- but we humans can't even be completely trusted with gunpowder and jet airplanes yet. *sigh*
Paleotechnologist and connoisseur of pretty shiny things.
Why is everyone so hung up on an energy-positive reaction? Antimatter is the ultimate in fuel for space-propulsion as it produces the highest theoretical amount of energy for the least possible mass. (i.e. 100% conversion - losses to nuetrinos that cannot be captured) This plays well into the rocket formula, giving antimatter drives a specific impulse unattainable with other rocket methodologies. In fact, the far-flung future may see c-ships traveling the stars based on matter-antimatter drives.
What I want verified is not if this process is energy efficient or not. I want to know if this process is several orders of magnitude more efficient than the current Fermilab and CERN processes.
Once again, antimatter catalyzation makes the fuel more efficient for its weight and thus plays well into the rocket formula.
Javascript + Nintendo DSi = DSiCade
Not really. We've already done the whole Cold War/Mutually Assured Destruction thing. Our weapons are already far, far larger than we could ever deploy here on Earth. Making them that much bigger only makes them that much more useless. At best, the only real advantage would be that they could be scaled down.
Until we start looking at warfare on an interplanetary or interstellar scale, our existing nukes and possible antimatter warheads are going to sit in their silos and go unused. Or in the case of antimatter bombs, I simply hope they're not built. The idea of a large-scale antimatter warhead being prevented from detonation by mere magnetic fields maintained by the nearest power plant is not an appealing idea. Just disrupt the power infrastructure for long enough and we'll blow ourselves to kingdom come. :-/
Javascript + Nintendo DSi = DSiCade
Does anyone know how much energy this takes? They mentioned the previous petawatt laser experiment that was decommissioned, but I didn't see where it mentioend the power required for this experiment.
The great thing about this for spaceflight isn't that it takes a lot or a little to produce antimatter, but rather that the density of usable energy is orders upon orders of magnitude greater than chemical or electric rockets. Denser energy leads to more fuel carried leads to greater delta v leads to semi-relativist flight leads to hate leads to suffering. These can even be used within the atmosphere to launch rockets from the ground easier than you can say "prompt gamma ray output".
Does anyone know if this might someday lead to antimatter plants? From a special on discovery, I heard that antimatter has a 100% mass to energy conversion, and uranium/plutonium is very expensive to enrich, so using gold for energy wouldn't be too impractical. This would be very exciting research if it does mean cheap energy at that scale with no pollution.
Help fight spam
Which eventually lead to the solution of bankrupting the USSR. (Something which would have eventually happened anyway, just much slower.)
Or, to be exact, it didn't happen.
Contrary to the popular belief, there indeed is no God.
Russia did not invade Vietnam. The United States invaded Vietnam because it is an historically paranoid state, and feared that communism would takeover east Asia were the grass roots movements of communists not exterminated. Similarly today, we're fighting them "over there" instead of "over here." It's just the manufacture of an enemy image that every government uses to maintain power.
Hell, when it comes down to it, why not let the Cubans take over Florida. After all if you stop them there's a risk of nuclear war.
Are you really afraid of the Cuban army? Really?
The Russians placed those missiles in Cuba because we placed missiles very close to their own borders. They made the mistake of thinking that it was okay to follow our lead.
And people in Florida would much rather live in peace under communism than die in a war.
What if you were right? Would you let any democratic principles get in the way of your own abject idealism?
Once the commies take over there will be peace.
Oh no! The commies! The reds, pinkos, the socialists! Run for your lives! Seriously. Only an insane person can turn cowardice into a call to arms.
After all, absolutely no one died in Russia or China or Cambodia after the Communist victory when they decided to get rid of their enemies.
And how many slaves and Native Americans did we kill in the last 200 years when we wanted to get rid of them? How many Vietnamese died before 1975 and after? How many dictatorships have we sponsored with our money and military technology?
You may not think there is blood on our hands, but we have plenty. I know you desperately want to get to the death toll numbers in your rebuttal, but imperialism and colonialism still take the cake for human misery. And if you don't think that America is an imperial empire... well. We have 700 military bases in almost every country of the world, and outspend the rest of the world in military expenditures. What else could I say.
Pedantic? Really?
To say nukes were only used once or twice is terribly misleading. Nukes were only used in a military capacity twice. Even more accurately, they were only used in a military capacity against strategic targets twice. They've been used for political posturing and military advancement approximately 2,000 times in various settings and with varied payloads.
This isn't intended to devalue the magnitude of the decision to effectively annihilate large numbers of human populations or suggest that testing is necessarily equivalent, just to remind you that the tactical application of nuclear weapons is not the only undesirable consequence of developing, distributing, and maintaining those weapons. Even unused nukes have serious consequences to the well being of humans and ecosystems in general.
The display of force in Hiroshima and Nagasaki demonstrated that the weapons were too morally reprehensible to use against human targets. The militarization of the United States and other nations has prevented critical assessment of the relative danger of these weapons from being reflected in policy until fairly recently. Check the graph on that wiki. Does it seem as if people suddenly became aware of the danger of nukes in 1945, or merely their effectiveness? And I'm not even getting into the tailings piles, superfund sites, government payouts to victims of testing, and so on.
Pedantic? Try having a complete thought before accusing someone of pedantry. There are more things going on here than the dramatic end of people's lives or your fantasies about interstellar warfare.
Where? In some natural magnetic field? Even, then... how are you going to extract it?
"Yes, Dr. Scott. A laser capable of emitting a beam of pure anti-matter." It looks like we can no longer shout back 'Then it's not a laser!' Yes, some of us are old enough to remember going to the Rocky Horror Picture Show before it was a cult classic.
You seem to be ignoring Israel already having nuclear weapons. And considering past behaviour, they're more likely to pull off a nuclear first strike than Iran would, should the latter ever get nuclear weapons.
Of course, if you made do with neutral antimatter you could clump it together, but then your magnetic containment won't work.
From scarped cliff or quarried stone she cries "A thousand types are gone, I care for nothing, no not one."
Twice?
For the record, we've dropped nuclear bombs on four countries.
Japan, Spain, US, Greenland.
Not all of them were on purpose, but that doesn't mean they weren't dropped.
http://en.wikipedia.org/wiki/List_of_military_nuclear_accidents
Three of the four countries still have radioactive material on the ground from them. And they just couldn't find it in Greenland.
There are two types of people in the world: Those who crave closure
Which raised the (very legitimate) question of why we were even in the conflict to begin with.
You should probably start your quest for answers with the French.
You're using the wrong calorie. Should be roughly 2.8 kg. Here's the calculation:
1 ton TNT == 4.184*10^9 J
mass equivalent m = 60 megatons TNT/c^2 = 2.5104*10^17 J / (9*10^16 m^2/s^2) ~ 2.8 kg.
It's commonly misunderstood just how much mass in a nuclear bomb is converted to energy.
Umm, all the time frames were quoted as from the point of view of the guy on the rocket.
He never said the rocket was traveling faster than light.
> you didn't account at all for relativistic effects at all.
It fully takes into account SR effects.
> A big question is how come you can travel faster than light
It doesn't. All times as for the people in the spaceship, as I stated. The reason it takes less time is because of time dilation.
> when you get to Vega everyone who sent you will be long dead.
Indeed.
Time dilation and distance contraction. This are special relativity effects.
For the people on earth, the ship takes 4 million years to travel 4 million light years at close to the speed of light. But for people in the rocket, it can be a very short amount of time.
> You left out where the energy to sustain 1 gee is going to come from
I gave the calculations for the energy/mass required to sustain 1g.
> Also with \gamma>>50 the blue shifted microwave background is not looking so nice.....
Shields :-)