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

[n2doc]

Imperial College London physicists have discovered how to create matter from light - a feat thought impossible when the idea was first theorised 80 years ago.

In just one day over several cups of coffee in a tiny office in Imperial's Blackett Physics Laboratory, three physicists worked out a relatively simple way to physically prove a theory first devised by scientists Breit and Wheeler in 1934.

Breit and Wheeler suggested that it should be possible to turn light into matter by smashing together only two particles of light (photons), to create an electron and a positron – the simplest method of turning light into matter ever predicted. The calculation was found to be theoretically sound but Breit and Wheeler said that they never expected anybody to physically demonstrate their prediction. It has never been observed in the laboratory and past experiments to test it have required the addition of massive high-energy particles.

The new research, published in Nature Photonics, shows for the first time how Breit and Wheeler's theory could be proven in practice. This 'photon-photon collider', which would convert light directly into matter using technology that is already available, would be a new type of high-energy physics experiment. This experiment would recreate a process that was important in the first 100 seconds of the universe and that is also seen in gamma ray bursts, which are the biggest explosions in the universe and one of physics' greatest unsolved mysteries.

more

http://phys.org/news/2014-05-scientists-year-quest.html

[bananas]

1. Now we can create dark bombs! nt

[bvar22]

2. OMG...They better not let that get away from them, or...

...we'll be drowning in matter every time the Sun shines!

[blackspade]

3. Now that is science!

[mindwalker_i]

4. There's got to be more to it than that

I suppose I should read the whole article, and I probably will soon.

Light doesn't collide. Photons are a class of "particles" known as bosons, which have integer values for their spin. Bosons can all occupy the same spot, or quantum state. In a laser, many photons are occupying the same quantum state. Helium also has a net integer spin, so it can form superfluids where the atoms all occupy the same state.

The point of the above is that one can't "collide" photons. I've heard that if a laser were made powerful enough, its electric and magnetic fields could be strong enough that energy from the beam would be converted to matter particles. I think high-energy gamma photons can become electron-positron pairs, and maybe that's what the article is talking about.

[xocet]

5. Here is an example of photons + a backscattered photon yielding an electron-positron pair...

This was done at SLAC, and the paper is from 1997:

POSITRON PRODUCTION BY LASER LIGHT

Kirk T. McDonald
Joseph Henry Laboratories
Princeton University, Princeton, NJ 08544
Representing the E-144 Collaboration

ABSTRACT
A signal of 106+/-14 positrons above background has been observed
in collisions of a low-emittance 46.6-GeV electron beam with terawatt
pulses from a Nd:glass laser at 527 nm wavelengths in an experiment
at the Final Focus Test Beam at SLAC. The positrons are interpreted
as arising from a two-step process in which laser photons are backscattered
to GeV energies by the electron beam, followed by a collision between
the high-energy photon and several laser photons to produce an
electron-positron pair. These results are the first laboratory evidence
for inelastic light-by-light scattering involving only real photons.


...

3.3 Positron Production

...

Pair creation via the interaction of two light quanta,

omega_plus + omega_naught -> e+ e- (26)

was first considered in 1934 by Breit and Wheeler,
who remarked that although the cross section is of
the same order of magnitude as the Compton-scattering
cross section, "it is hopeless to try to observe pair formation
in laboratory experiments with two beams of gamma-rays
meeting each other on account of the insufficiently large
densities of quanta." Indeed, this process had not been
directly observed prior to the present experiment. It is,
however, believed to be responsible for the fall-off of the
spectrum of astrophysical gamma-rays at very high energies.

The combination of an intense laser beam with the technique
of Compton backscattering brings the strong-field reaction (25)
within reach of laboratory investigation.

...

http://www.slac.stanford.edu/cgi-wrap/getdoc/ssi97-029.pdf

Here is the NYT article on the topic:

Scientists Use Light To Create Particles
By MALCOLM W. BROWNE
Published: September 16, 1997

A TRAILBLAZING experiment at the Stanford Linear Accelerator Center in California has confirmed a longstanding prediction by theorists that light beams colliding with each other can goad the empty vacuum into creating something out of nothing.

In a report published this month by the journal Physical Review Letters, 20 physicists from four research institutions disclosed that they had created two tiny specks of matter -- an electron and its antimatter counterpart, a positron -- by colliding two ultrapowerful beams of radiation.

The possibility of doing something like this was suggested in 1934 by two American physicists, Dr. Gregory Breit and Dr. John A. Wheeler. But more than six decades passed before any laboratory could pump enough power into colliding beams of radiation to conjure up matter from nothingness. The Stanford accelerator finally provided enough energy to do it.

Dr. Adrian C. Melissinos of the University of Rochester, a spokesman for the group, said in an interview that the weaker of the two light beams used in the experiment was produced by a trillion-watt green laser. That in itself fell far short of the needed energy, even though the pulsed green laser is one of the world's most powerful.

...

http://www.nytimes.com/1997/09/16/science/scientists-use-light-to-create-particles.html

For The Guardian article to say that &quot the process) has never been observed in the laboratory" is apparently false.

[kickysnana]

6. Transporters and time travel one more step closer. n/t

[Ichingcarpenter]

7. Sensational title it should read

Scientists Propose Collider That Could Turn Light Into Matter


Its still important news but sometime Phys.com over plays it sometimes.

Now where is my earl grey hot

[Javaman]

8. Tea. Earl Grey. Hot. nt

[BadgerKid]

9. For the Tea.Earl_grey.hot people

Okay, let's say you want to make a cup of earl grey tea from energy alone. For simplicity's sake, let's pretend you are providing the cup and the only thing you need to create is 250 mL (~8 fl oz for those of us in the benighted US) of pure water at 100 C. I chose 0.95835 g/cm3 as the density of H2O [wikipedia.org] @ 100 C.

Synthesizing that water from pure energy in a 100% efficient process that magically created only the appropriate molecules would require approximately 6,000 gigawatt-hours [google.com] of energy, aka 2.15E16 J (hooray for e=m*c^2 being on-topic for once in forever). FWIW, the absolute minimum amount of energy required is equivalent to over 5 megatons of TNT [unitconversion.org].

For reference, the generating capacity of the entire United States is approximately 1,000 gigawatts [eia.gov]. So, uh, in some mythical 100% efficient conversion of electricity to matter it would require the entire generating capacity of the United States for over 6 hours (line losses, oh my!) to produce the water for one cup of earl grey. If you want to stay true to concept, let's say your tea needs to be ready in 5 seconds. Okay, that represents 4.3 petawatts [google.com].

So, no, I doubt a ban will be what stands in the way of you getting your replicated earl grey.

Besides, anything that created that much power would be instantly weaponized.

http://science.slashdot.org/story/14/05/18/2139222/scientists-propose-collider-that-could-turn-light-into-matter

[Ghost Dog]

10. Ok, we have the hot water.

What about the all-important leaves, dry, then infused for just the right length of time?

[DetlefK]

11. Some more number-crunching.

http://www.democraticunderground.com/?com=view_post&forum=1002&pid=4972522

The mass of 12g carbon is equal to the energy of a nuclear bomb of 250 kt TNT.

And you can only create equal parts of matter and anti-matter from light.

[hunter]

12. I figure the machine is fed water and a "primordial soup" fluid of some type.

That way reconstructing food takes much less energy and you can simply dump excess hydrogen, oxygen, carbon, and nitrogen into the air as as H₂O, CO₂, N₂, O₂.

The sulfur compounds and other less common food components you'd probably dump as solids, so as not to stink up the mess hall.

Such a machine could also be used as a very potent weapon as it might be used to make things like nerve gas, even gasses tailored to kill a specific species but harmless to others.

An evil Captain Picard can have you killed a million different ways.