Scientists discover how to turn light into matter after 80-year quest

[JacobAldridge]

To be clearer, Theoretical Physicists have a theory about an experiment that would allow Experimental Physicists to prove a theory made by earlier Theoretical Physicists. They haven't actually conducted the Experiment.

"In Theory, there is no difference between Theory and Reality. But in Reality there is."

[scott_s]

I prefer the phrasing, The only difference between theory and practice is that in theory, there is no difference between theory and practice.

[frozenport]

I'll count my chickens when they hatch, lets wait until they do it.

[Noxchi]

So it's turning light into electrons? Isn't that already done with solar panels?

[pjc50]

No, solar panels turn light into the change of energy state of an existing electron. This is why they operate at the characteristic band gap voltage of the semiconductor from which they are made.

This experiment is about creating an entirely new electron/positron pair.

[chris_va]

Solar panels add momentum to existing electrons.

This is actually quite exciting.

[NickM]

Probably a long way off, but I can't help but imagine the kind of amazing applications something like this might have. If we could reliably capture and store the resulting positrons, then recombine them with electrons later to release the energy and harness it somehow, I'd imagine this could make for an energy storage system with some really interesting properties.

[troymc]

It is an interesting idea, but there are other ways, probably easier, to get the positrons. For example, some radioisotopes emit positrons as part of their natural radioactive decay process. See:

http://arstechnica.com/science/2011/02/positrons-at-center-o...

[fixedd]

Like the fact that light doesn't take up any space, so you could theoretically store an infinite amount of energy?

[ximeng]

Can anyone explain the vertical lines in the space time diagrams? Presumably not infinite velocity?

[yk]

They are not space time diagrams, they are Feynman graphs. Technically they are a clever way to write down the terms of a series expansion. In the convention used, on the left hand side are the incoming particles and the outgoing particles are on the right. The internal lines and vertices are just representations of formulas, and the important thing is only the topology of the graph.

However one of the really great things of Feynman graphs is, that they admit a easy interpretation about what is happening. Then the interior lines are interpreted as virtual particles that are created during the reaction, but since they are virtual they do not really have a defined speed, so the lines are just drawn like that.

[jessriedel]

Yes, it's infinite velocity. When you compute an amplitude from a Feynman diagram, you sum (integrate) over intermediate particle paths that are superluminal. The math is structured in a way that these contributions cannot actually be used to send signals, but the contributions are crucial and cannot be discarded. Essentially, they represent the relativistic generalization of the effect where one particle in a Bell pair "influences" another over a spacelike separation, but in a subtle and spooky way that cannot produce superluminal signaling.

[ToastyMallows]

How much energy is this photon/photon collier going to take? If a future experiment works, could we use this created matter to turn around and use it as energy? Or would that not be possible (i.e. - The energy used is far greater than the energy gained)

[timnic]

No, the energy gained will be equal or (most likely) less than the energy used. This is because we have conservation of energy, so a process like

energy (the original photons) -> matter (electron/positron) -> energy

can not produce more energy than was put in.

[Retric]

In cases like this energy is not really what you want to talk about as that's always constant it's USEFUL ENERGY which is interesting.

[nkozyra]

By no means is this my forte, but would this violate the conservation of mass?

[leephillips]

Mass by itself is only conserved in nonrelativistic classical physics. When you are in a relativistic regime the conserved quantity is a combination of momentum and energy. (You've probably seen E = mc^2, which shows that mass and energy can be transformed into each other.)

[asolove]

Conservation of mass is not applicable in the conditions under discussion, see Wikipedia's fun list of exceptions to conservation of mass: http://en.wikipedia.org/wiki/Conservation_of_mass#Exceptions...

[cboursnell]

Nope. As energy equals mass times the speed of light squared you're just converting energy into matter. It's just the opposite of what the atomic bomb does.

[timnic]

Mass is not a conserved quantity. Energy for example is a conserved quantity. So like in a nuclear fission reaction we loose mass but this lost mass is then converted into energy. I have not read the article in detail, but I suppose they want to turn part of the photons energy into masses for the electron and the positron. Mass and energy are linked via E = mc^2.

[ktran03]

Wiki:

The law of conservation of mass, or principle of mass conservation, states that for any system closed to all transfers of matter and energy (both of which have mass), the mass of the system must remain constant over time, as system mass cannot change quantity if it is not added or removed.

[dang]

A dupe of https://news.ycombinator.com/item?id=7763711.

[menubar]

Sounds like this theory could lead to creating one heck of a weapon, Dr. Venture.

[th0ma5]

Black holes probably do this?

[dmead]

there is no way this is not sensationalized.

[cLeEOGPw]

Imperial mages learn conjuration.

[gregorkas]

1. grab a flashlight 2. make your friend grab a flash light 3. turn them on and point them at each other 4. make it rain

[tlholaday]

My friend is so obstinate I cannot complete step 2, and now there is severe drought.