# How to produce enough power to create a pair of proton-antiproton?

I've recently discovered something great: the Schwinger effect. It says that if you concentrate enough power thanks to laser into a single point in space, it will spawn a pair of proton and antiproton. We could then create easily antimatter for interstellar travel, electricity production and more!

But there is a problem: you need to deliver 4.3e+29 watt. Lets imagine we have the lasers that are able to deliver this energy, how can we produce it? How much nuclear power plants would be required?

But as antimatter pairs are dangerous because their annihilation is powerful, we should build the "antimatter factory" in orbit in space (or should we?), we can't only rely on nuclear reactors, as they would be to costly to send in space. I've read that to power these lasers, we would need 2,000 kilometer square (20 times Paris' surface area) of photovoltaic panels.

It's a solution, but do we have enough materials on Earth to produce these gigantic and weak solar panels? Wouldn't the solution be to combine nuclear reactors AND solar panels, or rely on possible future energy sources as cold fusion?

Do you have a solution? thank you for your time and hopefully for your answers.

• $4.3 \times 10^{29}$ watts is a fairly meaningless number if you don't specify the duration. Delivering $10^{29}$ W for a nanosecond probably isn't that difficult (but will likely take longer to generate). Delivering $10^{29}$ W for a second or more is a whole different kettle of fish. Plugging "4.3e29 watts for 1 second" into Wolfram Alpha compares it to about 1/28,200 of the total amount of energy released by the Sun in a year, or 11 times the kinetic energy of the Moon in its orbit around the Earth. – a CVn Jan 7 '18 at 12:25
• Also, you may want to consider that matter-antimatter annihilation, while powerful, isn't exactly the end of the world. One unit of antimatter annihilates exactly one unit of matter. In doing so it'll spew a bunch of radiation all over the place that you'll have to deal with, but it's not like a small amount of antimatter is going to destroy a planet the way it's sometimes portrayed in fiction. I also dare say that antimatter, for the purposes of energy generation, isn't that different from e.g. gasoline; if you can keep it safely contained, it's a good store of energy, but not that much more. – a CVn Jan 7 '18 at 12:32
• For the materials for solar cells, for a-Si solar cell they are basically made of sand. Nuclear fission reactors will actually soon run out of fuel. The amount of available Uranium is limited. I think I read somewhere that if we would try to power the world with nuclear fission reactors uranium would be depleted within 10 years. The obvious solution to this is of course to use fusion reactor that huge hydrogen or lithium. ITER is working on a self generating lithium mechanism inside their fusion reactor. – D.J. Klomp Jan 7 '18 at 14:33
• Annihilating a quantity of anti-matter with the corresponding quantity of normal matter releases at most the same amount of energy which was used to produce the matter-antimatter pairs of particles in the first place. Antimatter may be a good battery, but it's not a source of energy. To answer your question directly: you cannot get out more energy than you put in. – AlexP Jan 7 '18 at 15:39
• @D.J. Klomp: Don't believe everything you read. A properly-designed reactor (called a breeder reactor) can produce more fuel than it consumes. – jamesqf Jan 7 '18 at 18:52

## 4 Answers

But as antimatter pairs are dangerous because their annihilation is powerful, we should build the "antimatter factory" in orbit in space (or should we?), we can't only rely on nuclear reactors, as they would be to costly to send in space. I've read that to power these lasers, we would need 2,000 kilometer square (20 times Paris' surface area) of photovoltaic panels.

I won't check the numbers, and as others have already told you, your energy requirements are way too high. If properly controlled - there is the difficulty - you only need around 8 kWh per pair. Since a solar panel will yield around 200 W per square meter, that's 40 square meters per hour: with 4 square meters you need ten hours, with 400 square meters you're ready in 1/10th hour, or six minutes.

But that's the minimum energy, not considering losses, not considering anything. How efficient matter-antimatter production is, it depends on your technology. With magnetic capture coils ready to snatch the antiproton, your energy requirements might increase to perhaps around 4000 m2h.

The problem now becomes that at energy densities way below those required for proton-antiproton pair formation, lots of other particle-antiparticle pairs will form. So the "spontaneous creation" method is either unfeasible or requires a way of separating and removing all those unwanted particles and if possible recycle their energy, meanwhile capturing those proton/antiproton pairs popping up every now and then.

What you need instead is a way of duplicating the cosmic ray smashing mechanism - accelerate protons at tremendous speeds using massive electric fields, bombarding larger nuclei so that enough protons create the conditions for a particle/antiparticle creation, and find a way for capturing the antiprotons. It can be done, for a cost.

Then you have another difficulty, that of storing those antiprotons. They're negatively charged and strongly repel one another - granted, they've got so much energy that you need very few of them, but as ℏe said...

And all matter is a mixture of positive protons and negative electrons which are attracting and repelling with this great force. So perfect is the balance, however, that when you stand near someone else you don’t feel any force at all. If there were even a little bit of unbalance you would know it. If you were standing at arm’s length from someone and each of you had one percent more electrons than protons, the repelling force would be incredible. How great? Enough to lift the Empire State Building? No! To lift Mount Everest? No! The repulsion would be enough to lift a “weight” equal to that of the entire Earth!

...so you really want to produce also a lot of antielectrons (positrons) and make antihydrogen. Except that hydrogen is neutral and cannot be held in place by ordinary electromagnetic fields. And you need to keep it in a vacuum, but how do you keep a gas in a vacuum? So you need to supercool and weakly compress it using diamagnetism.

All this will impact your power demands, unless you come up with some other means of containing antiprotons that also allows for antiprotons to be easily extracted and annihilated (remember, each pair only gives out about 8 kWh). There are ways, but not so economical.

• okay, so if a proton antiproton pair production requires about 8k/h, how much electricty does a positron electron pair production require ? – Mathis Jan 12 '18 at 15:50
• Energy is related to mass and the mass ratio between protons and electrons is μ = mp/me = 1836 (Wikipedia). So, that's a paltry 4.35 Wh -- or the equivalent of a 1180 mAh 3.7V LiIon phone battery. (That is what you can get out of a e/p pair annihilation, with the very unrealistic assumption of being able to convert it with 100% overall efficiency). – LSerni Jan 12 '18 at 17:06
• Okay but i dont understabd something: what are you telling me is it the energy required to cause a pair production or how much energy us released from a antimatter matter annihilation? – Mathis Jan 12 '18 at 18:40

The Schwinger effect you are talking about is where the solution of two overlapping maxwell equation is another maxwell equation. These are you virtual particles. This solution is only possible in the non linear regime at very high electric field strengths. The non linear regime starts at a field strength above 1x10^18 V/m, so you would need to be above this limit. So this is really talking about creating particles out of nothing than creating particles from another particle with collisions. From the literature the particles will be a electron and positron pair, not a proton anti-proton pair.

So it is not really an energy question but electric field strength. You can create this electric field with a laser and amplify the strength by focussing the laser. Some of the most powerfull lasers today are coming close to the limit such as the L3-HAPLS at ELI or the HYPER project.

So if you have this particle how much energy do you get? A positron and electron will annihilate each other transforming their mass into energy in the form of two photons. These will have an energy of 2x0.511 MeV or about 1.64x10^-13 J, so very little energy. So the question will be at what rate you produce these elements, this is calculated in the original paper of Schwinger.

More practical I actually doubt whether you would even get a fraction of the energy out you need to put in.

I really think you are re-inventing the wheel. Nature has been doing this for a very, very long time, and without your huge expenditure of energy.

Perfectly safe to do it on earth.

If the lightning had directly generated pairs of electrons and positrons, one would expect to detect gamma rays from annihilated positrons immediately after the lightning, not 35 seconds afterward, Enoto said. Instead, the annihilated positrons the researchers saw likely came from lightning-triggered nuclear reactions.

Just mimic nature's own CERN lab. use lightning.

The trick is not in the production, the trick is in the capture and containment. Nature, apparently, produces all the 'stuff' we could ever need, in an ongoing basis. We just don't know HOW, exactly.

So 'all we need to do is' mimic and/or harness lightning.

# I don't know where you get $10^{29}$ W

The process of creating a particle-antiparticle pair is called pair production. To produce this pair, you need a boson with sufficient energy. The Mass-Energy of both a proton and an anti-proton is about 938 Mev/c$^2$. Translated into Joules, this mean you need about 27 MJ to do so. I don't know how you get from here to $10^{29}$ W.

I understand that this is generally done by either smashing two extremely high energy photons together, or in an electron-positron pair collision. A laser isn't really the way. A laser generates light at a certain wavelength. Wavelength is directly related to energy by $$E = \frac{hc}{\lambda}.$$ For a 27 MJ photon, the wavelength would have to be unimaginably small; well outside the range of any laser currently produced, something like $7\times10^{-33}$ meters.

Just considering that each photon emitted by the laser would need energy greater to the total output power of the most powerful lasers around today. You don't need a whole laser of photons of this power, you just need one.

• Just to put that $7 \times 10^{-33}$ meters into perspective, Wikipedia puts the gamma rays part of the EM spectrum down with a shortest wavelength of 1 pm, or $10^{-12}$ meters, equal to 1.24 MeV. Even the claim of 10 TeV from astronomical sources would, if I'm not mistaken, result in a wavelength of some $10^{-19}$ meters; still far longer than what we're dealing with here. – a CVn Jan 8 '18 at 18:57
• Thank you for your answer kingledon but i thought a proton antiproton pair production could only be caused by concentrating at least two energetic photons together, how can only one energetic photon cause a pair production, without interacting with an other particle? – Mathis Jan 8 '18 at 19:03
• Also what would be the least energetic photons (wavelength) capable of causing a proton-antiproton pair production (and how much?)? if they were to be shot by lasers, how much electricty would the lasers need? – Mathis Jan 8 '18 at 19:05
• I think you meant "generally done by either smashing two extremely high energy protons together" – Loduwijk Jan 8 '18 at 19:15
• For the specific question at hand, it is about using photons, yes. However, proton/anti-proton pairs are generally created by smashing protons together. That is how particle accelerators like CERN or LHC work. They accelerate protons to near light speed and then smash them into other protons. – Loduwijk Jan 8 '18 at 19:37