Engineers Propose Interstellar Spacecraft Fueled by Lasers

[PingoBlack]

Artificially produced positrons can be accumulated into beams (Link [http://www.sciencedaily.com/releases/2007/10/071024090816.htm]), and although splitting electron-positron pairs is challenging, it is possible (according to the wikipedia article on particle-antiparticle pairs). I am by no means knowledgeable in this field, but I imagine it could be done by creating the pairs in a two-dimensional plane, and the applying a magnetic field perpendicular to this plane, making the positrons and electrons split up to each side of the plane. Then it's just a matter of using magnetic lenses to focus them. Actually confining them is of course a real problem, but it is already being done in CERN where they study anti-hydrogen.

Possibly I'm just being too careful.

I mean in theory, the two particles should separate if the electric field was strong enough to send them appart before they destroy each other ... But only time I ever heard about splitting a quantum pair it took a black hole's event horizon to do it.

Of course, this being quantum physics, it is mindbogglingly hard to know the energy required unless your last name happens to be Higgs. Or one of his colleagues, hehe.

 

[Pinkamena]

Artificially produced positrons can be accumulated into beams (Link [http://www.sciencedaily.com/releases/2007/10/071024090816.htm]), and although splitting electron-positron pairs is challenging, it is possible (according to the wikipedia article on particle-antiparticle pairs). I am by no means knowledgeable in this field, but I imagine it could be done by creating the pairs in a two-dimensional plane, and the applying a magnetic field perpendicular to this plane, making the positrons and electrons split up to each side of the plane. Then it's just a matter of using magnetic lenses to focus them. Actually confining them is of course a real problem, but it is already being done in CERN where they study anti-hydrogen.

Possibly I'm just being too careful.

I mean in theory, the two particles should separate if the electric field was strong enough to send them appart before they destroy each other ... But only time I ever heard about splitting a quantum pair it took a black hole's event horizon to do it.

Of course, this being quantum physics, it is mindbogglingly hard to know the energy required unless your last name happens to be Higgs. Or one of his colleagues, hehe.

To split a spontaneously created quantum pair, you'd need as much energy as the two particles have combined. So let's say, due to quantum fluctuations, a electron-positron pair is created. They want to annihilate really quickly in order to not break the conservation of energy, but if you can give the two-particle system enough energy to not break that law, they should keep existing. The energy needed would be the energy equivalent of the rest mass of both particles, namely 2*0.51 MeV. This could be supplied by a laser.
An easier way of creating the pairs would be to bombard a high-density target with heavy atoms such as lead or uranium with gamma radiation. If the gamma photons have an energy larger than the rest mass of the two particles you want to create, the gamma photon will be transformed into them.

 

[Vhite]

Yay! I've been transported into sci-fi universe!

 

[Agayek]

Rockets doesn't use fossil fuel, but usually hydrogen and oxygen. Your point still stands, though. The energy released from chemical reactions is much too low for practical space exploration.

Huh, learn something new every day. I coulda sworn rocket fuel was generally petroleum based. Oh well, that combo makes more sense anyway now that I think about it.

 

[Desaari]

Sadly with NASA's budget cuts this is a long long way off. If only NASA had more money.

Although I also wish those budget cuts didn't occur, I'm not sure what NASA has to do with it.

 

[Xan Krieger]

Sadly with NASA's budget cuts this is a long long way off. If only NASA had more money.

Although I also wish those budget cuts didn't occur, I'm not sure what NASA has to do with it.

I thought they were in charge of everything that had to do with space. Let me guess, I'm an idiot, right?

 

[Rabid Toilet]

Huh, learn something new every day. I coulda sworn rocket fuel was generally petroleum based.

Nope, they basically run on water. Neat, huh?

On topic: I'm not going to pretend I know enough about antimatter to understand the details of this. It's always exciting to get advancements in interstellar travel, though.

 

[Xan Krieger]

Sadly with NASA's budget cuts this is a long long way off. If only NASA had more money.

Although I also wish those budget cuts didn't occur, I'm not sure what NASA has to do with it.

I thought they were in charge of everything that had to do with space. Let me guess, I'm an idiot, right?

These days the majority of awesome space stuff happens either through private enterprise or international cooperative ventures. NASA hasn't really lead the way for quite some time, given how massively underfunded they are.

Thank you, I am indeed an idiot. I do understand all the physics of this, I just don't know the major players anymore.

 

[008Zulu_v1legacy]

Weight means a hell of a lot in space, to be perfectly honest. The more something weighs, the more force is required to get it to move. The more force is needed, the more energy is required. The more energy is required, the more fuel is needed to generate said energy. Which means more weight, which means more fuel, etc etc.

Keeping spacecraft relatively lightweight is one of the more important aspects of their design. We're not going to have good space travel until we completely (or close enough as to not matter) stop using fossil fuels in them, primarily because the weight:energy ratio of fossil fuels simply isn't good enough.

Weight only counts if you're in any sort of gravity well or the ship is big enough to generate its own.

 

[Agayek]

Weight only counts if you're in any sort of gravity well or the ship is big enough to generate its own.

If you really want to be pedantic. Replace "weight" with "mass" and my point stands.

More weight means it takes more force and therefore more fuel to a) get up to speed, b) change direction, c) slow down, and d) counteract the affect of relatively local gravity sources.

Momentum and impulse is a ***** like that.

Also, since we're being pedantic, you're always in a gravity well.

 

[Therumancer]

snip

You seem to get awfully worked up over names. I don't think what a thing is called has much influence over how well the physics behind it works. It seems weird to me how much you're focusing on that. Your language conveys a picture of a person sitting at his keyboard shaking with rage at their choice of name.

OT: Very cool; the weight of fuel is a seriously annoying problem in space travel. Even if this doesn't work, I think it's definitely a step in the right direction.

I'm more snickering at irony than I am "shaking with rage". If you read what I've written you'd know that I suspect it's a joke. The name and description seems like a high brow joke for science fiction nerds, the kind that noone else would get. That it might be serious just makes it funnier.