
Scientists discover how to turn light into matter after 80-year quest (2014) - peter_d_sherman
https://phys.org/news/2014-05-scientists-year-quest.html
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ChuckMcM
This is from 2014 and proposes the experiment. Follow ups have been
interesting, here is one from 2017
([https://www.nature.com/articles/s41598-017-17605-6](https://www.nature.com/articles/s41598-017-17605-6))
which actually generates positrons.

And here is the discussion from 9 months ago:
[https://news.ycombinator.com/item?id=15725759](https://news.ycombinator.com/item?id=15725759)

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mirimir
Damn, I hate it when they confuse theory, modeling and experimentation! In the
cited discussion, splittingTimes noted:

> Since 2014 I can find 34 citations, none of which are an actual experimental
> realization of their scheme [1]. ...

So has that changed? Or is this just theory and modeling?

~~~
ChuckMcM
Sadly it hasn't changed as far as I can tell. The nature paper cited helps
summarize some of the approaches being considered.

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UpshotKnothole
My lord, who wrote this article?

 _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._

They didn’t discover it, as they say in the same sentence this is an 80 year
old theory, rather they demonstrated it _in a lab_ rather than observing it in
nature. That sentence also makes it sound like this process may have been
considered impossible until they demonstrated it in the lab, and that is just
not true.

Plus this stupid site clipboard hijaacks. Feh.

~~~
mirimir
The article implies that they "demonstrated it in a lab". But actually, they
just imagined a way to do that. And as far as I can tell, it hasn't yet been
tested.

How is it that some physicists seem to talk about results of modeling as if
they were experimental results?

~~~
whatshisface
Photon-photon scattering has been observed:
[https://en.wikipedia.org/wiki/Two-
photon_physics](https://en.wikipedia.org/wiki/Two-photon_physics)

~~~
mirimir
OK, but that's not Breit and Wheeler "photon-> <-photon" to "<-electron
positron->", right?

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Insanity
That's quite neat! Maybe important to note that they have described an
experiment to test the theory but not conducted an experiment yet. :)

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xref
For reference it looks like the uniqueness here is they are using lasers
(photons) for electron-positron pair production.

Particle colliders like LHC and it's progenitors all create matter as a
fundamental part of their operation, but I guess they're classifying that as
"energy" to matter not "light" to matter.

~~~
InclinedPlane
The uniqueness isn't just that they are using lasers (that's been done) but
that they are using only lasers. There are many different ways you can get
pair production from high energy photons, one of the easiest is via an
interaction with a charged massive particle (such as an electron, proton, or
atomic nucleus). But it's also possible for pair production to be a purely
photon only process (just as the reverse process of annihilation producing
only photons is possible), however that is a lot more difficult to pull off
experimentally.

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jasmcole
The experiment described here was performed by a couple of groups
independently earlier this year. Data is being analysed, so fingers crossed!

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mirimir
Really! Can you share any specifics, cites, etc?

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JimA
1) Create plausible way to confirm 80 year theory

2) Say that the only way to test requires "slabs of gold"

3) Profit?

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tCfD
It worked for the alchemists!

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berbec
Seems, from reading, they see actually turning matger and light into matter.
Multiple lasers, yes, but there looks like matter being consumed in the
process.

~~~
kadoban
In my reading, there would be thermal radiation (aka light) and a high
intensity photon beam (aka light) interacting to create particles.

I didn't see matter being consumed anywhere, did I miss it?

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jacquesm
Using a couple of lasers to create matter makes a whole bunch of weird things
possible. And while we're dreaming, this would be one heck of a 3D printer,
provided you'd be willing to wait a literal eternity for your device or
product!

Anyway, obviously that's still science fiction but this at least opens the
door.

~~~
skinner_
Here's something even crazier: Are photons in vacuum, with photon-photon
scattering, IN PRINCIPLE a model with strong enough computational power? I
don't have any specific application in mind, but just for the kicks, how cool
would it be to create a galaxy-sized computer that has no parts other than
photons? I don't mean "no _moving_ parts other than photons", I literally mean
a photonic computer where even the reflectors are made of other photons.

~~~
jacquesm
Someone beat you to that idea by about 8.9 billion years.

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amai
Relevant Wikipedia article:
[https://en.wikipedia.org/wiki/Breit%E2%80%93Wheeler_process](https://en.wikipedia.org/wiki/Breit%E2%80%93Wheeler_process)

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tkmo
Would this be able to be used as a fuelless space propulsion method?

~~~
yetihehe
Yes, but it's SO impractical as to be unusable (remeber, that E=mc^2, so
m=E/c^2, which means m is REALLY small).

Edit: You will get very small amounts of matter from energy. Small amounts of
matter will mean very low thrust. Much better use of that amounts of energy is
just collecting interstellar medium and accelerating it.

~~~
kiriakasis
it is worse than impractical actually light is the best propulsion method per
energy consumed (as propulsion efficiency depends on speed) it is just that to
expel a given mass of light you also need a huge dead weight to emit it.

it would be way more useful to have a method to turn matter into light. this
would be a fantastic low power space engine.

(not really an expert, but pretty sure about this)

~~~
Tor3
Well, to turn matter into light is basically the same as turning matter into
energy.. which will, of course, produce a lot of it: E=mc^2

That's really hard though, unless you use antimatter+matter. And then you'll
have to produce the antimatter first, of course. And you're back to square
one.

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rsynnott
> And you're back to square one.

Well, not necessarily; if you could efficiently produce and store antimatter,
that'd make a hell of an energy storage mechanism, and possibly make
interstellar travel feasible. That's a HUGE if, obviously.

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SketchySeaBeast
That right there is a fuel with a Roland Emmerich scale for potential
(nuclear) fallout. Can you imagine trying to sell that to the public? "Combine
the worst parts of both Challenger and Chernobyl." The public doesn't really
accept normal nuclear power plants.

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monocasa
Don't do it on earth, do it somewhere else in the solar system.

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dark1999
This is from 2014.

~~~
Insanity
Completely missef that. Should probably be added to the title.

