Scientists Propose Collider That Could Turn Light Into Matter 223
An anonymous reader writes "Imperial College London physicists have discovered how to create matter from light — a feat thought impossible when the idea was first theorized 80 years ago. From the article: 'A pair of researchers predicted a method for turning light into matter 80 years ago, and now a new team of scientists are proposing a technique that could make that method happen in the purest way yet. The proposed method involves colliding two photons — the massless particles of light — that have extremely high energies to transform them into two particles with mass, and researchers in the past have been able to prove that it works. But in replicating that old method, known as Breit–Wheeler pair production, they had to introduce particles that did have mass into the process. Imperial College London researchers, however, say that it's now possible to create a collider that only includes photons.'"
You're doin' it wrong (Score:5, Funny)
Dudes, you are solving the problem, in reverse: we want instant energy from dirt.
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...soylent electrons??
Backwards? (Score:5, Funny)
What am I missing here? (Score:5, Informative)
I preface this with an admission that my serious physics studies were like 25 years ago now, but - photons are bosons, how can they "collide"?
Re:What am I missing here? (Score:5, Informative)
Being bosons just means you can pack multiple quanta into the same state.
All particles interact (otherwise, how would we even know they "exist"?), and photons interact electromagnetically. That means that they can induce the vacuum to produce pairs of electrically charged particles: say, an electron and a positron. Usually, those particles are just quantum fluctuations or "virtual particles", living for a tiny fraction of a second due to Heisenberg uncertainty. However, if two photons have enough energy between them (at least equal to the mass-energy of the pair), they can give their energy to the electron and positron and turn them into real particles. That's what they want to do here: get two photons to give their energy to a virtual particle pair, making it real.
Re:What am I missing here? (Score:4, Informative)
Thanks for that, I knew they interact but I didn't think they could "collide" per se, and from your explanation maybe "collide" is just the wrong word to be using?
Re:What am I missing here? (Score:4, Informative)
Re:What am I missing here? (Score:4, Insightful)
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It's all about the speed at which the waveforms can react to the difference imposed on them. At lower energies, the photon waveform can react faster than the energy in the interaction (not a collision). But once you go beyond a certain point, the particle's waveform cannot react fast enough to the interaction and they two collide to cause differences in each particle.
Re:What am I missing here? (Score:5, Interesting)
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Apologies, I'm not a physicist but ... if you create electron and positron, wouldn't they annihilate each other immediately again? Or do you somehow find a way to separate them?
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photons can scatter from each other (its just that the cross sections are low)
https://en.wikipedia.org/wiki/... [wikipedia.org]
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Empty space isn't that empty. You can get virtual pairs of electrons and positrons appearing and disappearing. They pop into existence because they can, even in empty space, but the have negative energy and a virtual wavelength, so they are almost bound to re-coalesce, and the energy of their recombination will exactly equal the energy of their creation, so they pay back all the energy they 'borrowed' and disappear without trace. However, if a photon turns up at this critical moment and pumps in the energy
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That also helps, thanks.
Discover is the wrong word (Score:4, Insightful)
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I don't know, if they're the first to devise a working setup to achieve that, haven't they discovered how to do it?
It was already discovered that it should be possible, but they might be the first to actually describe a possible apparatus to do so, so i guess it's fair to say that they discovered how to do it?
Comment removed (Score:5, Informative)
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Re:Discover is the wrong word (Score:5, Informative)
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"It would be a huge shock if a properly conducted experiment would fail to produce the expected results."
Right. Whereas if it were a theory it would be impossible.
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You're incorrectly defining theory to mean "truth" or some weaselly variation of that.
A theory is a descriptive framework, today usually mathematical. A hypothesis is a specific prediction based on a theory. The theory of QED describes how photons can create matter particles under certain circumstances. An experiment can be designed using that theory, with the hypothesis that if you shoot high energy photons into a chamber prepared in such and such a way, electrons and positrons will come out.
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A hypothesis is an educated guess to explain an observation of reality. A hypothesis is not a prediction of anything. Predictions are made to test a hypothesis. A hypothesis that is thoroughly tested is called a theory, especially one which encapsulates many tested hypothesis (again, with it's own confirmed predictions).
You've got your order of operations wrong. The first step in the s
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You keep using that word. I don't think it means what you think it means.
Something that is probably true but remains unproven is a hypothesis. It doesn't become a theory until it is proven.
The way the public uses the term is not the same as the way science uses it. The public uses theory to refer to speculation. That would be hypothesis at best. All the predictions that can be derived from your "guess" have to be tested, and then those tests succe
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"Something that is probably true but remains unproven is a hypothesis. It doesn't become a theory until it is proven."
You're using the term incorrectly. The way the "public" uses it is closer to the scientific definition.
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Well, to be honest, they've asked for funding to do the obvious experiment to test it. It's not particularly clever, only expensive. And, as has been pointed out repeatedly above, they haven't "discovered" this, it is part of the standard lexicon of QED and has been for maybe 60-70 years.
A clever way of testing it would be to use e.g. a free electron laser like the one we already have at Duke and shoot the laser beam into a "wiggler" -- a region of alternating crossed fields -- well downstream of the circ
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This experiment is testing a prediction of a hypothesis. The hypothesis is based on observation, predictions are based on the hypothesis. QED is being tested here. There being a testable and untested prediction that must be true to confirm QED technically makes it a hypothesis. This prediction was previously thought untestable therefore it was called a theory. All the other test
This was already done back in 2001 (Score:2, Informative)
Light was already turned into matter back in 2001 by Lene Hau at Harvard.
When the light pulse disappeared, the mass of the sodium increased.
http://www.seas.harvard.edu/ha... [harvard.edu]
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You know how we know that you didn't even bother to read the excerpt?
Re:This was already done back in 2001 (Score:5, Informative)
What? How can you link a paper like that and completely not understand its contents? No, they did not create matter out of light. The important thing from that paper is that the light was frozen in place while it was traveling through the material. It's a nice experiment, but has absolutely nothing whatsoever to do with photon-photon interactions and creating of particle-antiparticle pairs. The word "mass" doesn't even appear in the paper, for example. The photon energies are eV level in that paper, and photon-photon interactions require billions times more. Like, gamma rays, not visible light.
You might argue, pedantically, that while the light was trapped in the sodium in that paper, the kinetic energy of the sodium atoms increased. And due to relativity, increase the kinetic energy of something also increases its mass. Well, you would be right, and that happens every time the sun shines on something and warms it up. But when you talk about creating matter from photons, they mean making brand new particles-- that is, making even the *rest mass* portion of their energy out of the photons-- not just speeding up existing particles. And that just cannot be done with light near the visible spectrum.
Mod up! (Score:2)
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What? How can you link a paper like that and completely not understand its contents?...
I was in communication wi. Dr. Hau in 2007, and she indicated that the sodium mass had indeed increased when the probe pulse was stopped.
This was also done back in 1997. (Score:5, Informative)
Back in 1997 at Stanford green laser light was smashed into gamma rays to produce matter. [bibliotecapleyades.net]
Scientists Use Light to Create Particles
Photons of light from the green laser were allowed to collide almost head-on with 47-billion-electronvolt electrons shot from the Stanford particle accelerator. These collisions transferred some of the electrons' energy to the photons they hit, boosting the photons from green visible light to gamma-ray photons, and forcing the freshly spawned gamma photons to recoil into the oncoming laser beam. The violent collisions that ensued between the gamma photons and the green laser photons created an enormous electromagnetic field.
This field, Melissinos said, "was so high that the vacuum within the experiment spontaneously broke down, creating real particles of matter and antimatter."
This breakdown of the vacuum by an ultrastrong electromagnetic field was hypothesized in 1950 by Dr. Julian S. Schwinger, who was awarded a Nobel Prize in physics in 1965.
Emphasis mine.
Thus, we do know that we can create matter by colliding photons already. The new experiment proposed could be useful because it does not require the electron-photon collision near the detector in order to produce the gamma photons and subsequent light on light reaction. They'll be firing gamma rays through a cylinder full of black body radiation. A gamma-gamma collision would be more interesting, IMO. The new gamma or black-body radiation collision experiment should be of even lower energy than the gamma and green laser collisions which produced matter in 1997.
Why even go for a lower energy apparatus than what has been demonstrated at all? Simple: To verify the minimal energy level required to make the vacuum puke.
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Also see
http://www.slac.stanford.edu/e... [stanford.edu]
It was actually done much earlier but generating matter by scattering off of virtual photons. The SLAC experiment was actually looking for (and found) nonlinear interactions in photon / photon collisions. (as were predicted by QED).
The next question is... (Score:3)
How often do this happen in the "real life" universe?
What is the threshold for creating matter from light? Can there be some factor not yet discovered where some matter is re-created from light in the universe today?
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But how much energy is required - and which particles don't we know about yet that can lead to a transformation and aggregation into new matter?
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E = MC2
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dammit. MC squared, duh,
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I experience this on a daily basis. I meet people who appear bright, but soon after turn out to be very dense. I can only guess there is a light to matter conversion there.
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Very large stars create matter from light in their core. Although, in order to conserve momentum, it happens most commonly near a nucleus with a single photon. The photon converts to a positoron and electron and the nucleus recoils a bit conserving momentum. I expect that in the giant randomness of a stellar core gamma rays occasionally collide head on thus allowing momentum to be conserved that way, but I expect it is much rarer than the other mechanism, since at those densities a gamma ray probably enc
What element would it be? (Score:2)
So what kind of matter would be produced? Some element we are already familiar with, or something entirely new?
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RTFA - you wouldn't get any element.
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Re:What element would it be? (Score:4, Insightful)
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positronium is not an abundant element
One thing is certain (Score:3, Funny)
No matter the result, they'll surely be able to make grant money go poof at the speed of light.
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No it doesn't. That money gets spend and circulates. It doesn't go 'poof'.
some physicists work on real physics. (Score:5, Funny)
I don't really use that analogy, it just occured to me and now i am sad.
Um, Praxis (Score:2)
Um, Praxis
http://www.youtube.com/watch?v... [youtube.com]
So just shine two flashlights at each other... (Score:3)
Sometime in the next few hours, quantum mechanics would predict a particle or two being emitted.
Oh, you want to measure that against background noise? I guess you'll need a bigger flashlight. Maybe try the big six-cell ones.
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Re:how soon before (Score:5, Informative)
I believe the summary is confusing concepts. A 'proposal' for how to do something, but not actually having implemented the proposal to see if it actually works IS NOT the same as 'discovering how to do something'.
There is a huge, fundamental gap between
I suggest we try doing X to accomplish Y
and
I did X and accomplished Y
Re:how soon before (Score:5, Informative)
Not at all. In science, there is just as much validity to "we did X but didn't get Y" as there is to "when we did X, Y was accomplished." In fact, Michelson and Morley are a prime example of "we did X but didn't get Y" in 1887, and they won the Nobel prize for it in 1907.
Re:how soon before (Score:5, Informative)
Not entirely devoid, no, but in my experience (as a former researcher; still have the CERN employee ID card) there is still some that is free of politics. The fact that results need to be reproducible to be accepted helps. The main concern is funding. As long as you can confidently tell your backers that there is money to be made either way, or find different backers with vested interests in different results, there is no pressure to fudge results. In fact, the project I worked on (ATLAS) had no outside input asking for bias in results that I could see in any way, shape or form. Of course, if that was the case universally nobody would question vaccines, but it still happens often, especially in fields like particle physics (which this article is talking about) in which application is so far down the road that most financial backers really are looking for the spinoff technology it takes to produce the result moreso than the result itself.
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Well, either the math or the science. And if we were 100% sure the science would work there'd be no point in doing the experiment.
Re:Energy-matter synthesis (Score:5, Insightful)
My first thought was 3d printer. Imagine deposing one atom tick layers of any element in any shape. eg; The Star Trek synthesiser.
But that wont happen because they'll ban the thing over irrational fear before the technology reach the point it can print a cup of earl grey.
Re:Energy-matter synthesis (Score:5, Interesting)
But that wont happen because they'll ban the thing over irrational fear before the technology reach the point it can print a cup of earl grey.
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.
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Re:Energy-matter synthesis (Score:5, Insightful)
If you assume we have a way to convert energy into matter with 100% efficiency, then it's not far fetched to assume we'd also have a way to convert matter into energy. So, you can save yourself all the calculations, and just grab 250 grams of waste products from the ship's waste disposal system, and turn them into a cup of Earl Grey tea.
So, uh, at that point why are you even bothering with a matter/energy conversion? Just use the cleaned, recycled water directly. I already have a machine that can "3D print" a cup of 95 C water, and all it requires is a water reservoir and a 1300 W heating element. I have to bring my own cup, but that was already stipulated.
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Ah, but it can it also create the necessary flavoring to create something which tastes almost, but not entirely, unlike tea?
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Ah, but it can it also create the necessary flavoring to create something which tastes almost, but not entirely, unlike tea?
Yes, but they're trying to refine the process such that it doesn't also create a sperm whale and pot of petunias as a byproduct.
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Re:Energy-matter synthesis (Score:5, Insightful)
You have forgotten that no process will be perfectly efficient unless someone invents some new thermodynamics. You are talking about "waste" of a few hundred grams of easily-recycled organic matter (or water) by channeling megatons worth of energy. What's a few percent of waste heat generated on a process that is pumping quadrillions of joules around? Entropy always gets its pound of flesh.
But hey! We *saved* some water we could have, you know, could have distilled into purity using today's technology by using an infinitesimal amount of that waste heat that would be inescapably generated by pumping around those megatons of energy for pointless matter/energy conversions!
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Dudes 3D printer is essentially the star trek replicator. If you can't see how a replicator is useful you are a hopeless cause. Also, there is nothing to say the waste from inefficiency in the process has to be heat.
In an imaginary world where we can replicate anything by converting energy into matter an atom at a time we can convert matter into en
Re:Energy-matter synthesis (Score:4, Insightful)
Current thermodynamics works fine enough for what is suggested. Thermodynamics allows for next to ideal conversion.
Gotcha. So, in order to avoid boiling some water to distill it to purity, you're going to be doing a matter/energy/matter conversion. In order to come out ahead of using a simple boiler, your ~9 petawatt (two conversions in the requisite time doubles the power) process is going to need to be 99.99999999% efficient or so.
Even a 99% efficient process would dump 90 terawatts of waste heat. The waste heat of your process would represent approximately 1/10 of the power of an average hurricane [noaa.gov]. Remember, you're claiming we would do this in order to "save energy" by not distilling a quarter liter of wastewater.
In summary: just because science develops a method that allows something to be done does not imply it will ever be the favored technology. We developed the means to create gold via atomic bombardment a long time ago, and that process will never supplant gold mining.
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The way I see it, it's like putting in energy to convert water to steam, pump the steam to the dispenser and then extract the energy again to condense it to water. If that energy is just stored somewhere, and used to heat the next batch of water (assuming 0 loss which goes against entropy) you only need the energy to pump the steam about.
If you have solid matter in one form, and know a process similar to boiling that converts it to energy, then pump it as 'light' to the dispenser, you then can reverse the p
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Since we are speaking of mythological devices here, the franchise which contains this mythical replicator has proclaimed that the ship that powers the replicators can regenerate up to 4,770,000 TeraWatts.
Go here to get your SiFi Geek On [ditl.org]
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Re:Energy-matter synthesis (Score:5, Insightful)
I'm afraid that we've already got everything we need to make a much more comfortable society even with "just" the technology and resources we have now. That fact that we don't shows that something else is hard-wired into our biology: how to be complete and utter assholes.
I suspect even with completely free everything we'll still find ways to have taxes and rich and poor people.
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Makes you wonder, do we need these complete and utter assholes? They say that a statistically significant number of CEO's would pass, or fail, (depending on your POV) a standard test for psychopathy.
Was the chieftain of the old wattle and daub hut village a psychopath? Was he out for his own interests and needed to use all those around him to get it? Was his goal to provide himself with a nice big hut to live in, but in order for that to happen he needed to be charismatic and persuasive, and ultimately all
Re: Energy-matter synthesis (Score:2)
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true but that same progenitor might also bind those same monkey on one planet so that they don't threaten every other planet with their ways.
Do you want to go to the stars? Or do you want to be stuck on earth were 50% of the population are morons?
Re: Energy-matter synthesis (Score:5, Funny)
Or do you want to be stuck on earth where 50% of the population are morons?
Fixed that for you.
Regards,
The other 50%
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But you couldn't be bothered to capitalize Earth ...
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Just curious - do you think that the 50% who are morons includes those who can't spell "where"?
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By definition, 50% of the population are not morons.
It's like saying 50% of the population are geniuses.
Re:Energy-matter synthesis (Score:5, Informative)
Total energy output of the sun per second: 3.8×10^26 J (source: wikipedia)
This amounts to 4.22×10^9 grams per second,
or about 18 million cups of tea per second.
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That's barely enough to satisfy British demand, let alone that of the civilized world. And we haven't even figured in energy needs for beer production, yet.
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If you compare the energy output of a single power station today to the energy output of all the camp fires in one night of prehistoric human history, it probably seems like a massive difference.
We know that future technology will be orders of magnitude bigger / more powerful than current technology.
And it's cool to think that, maybe, when you have a warp core that powers a space ship going FTL with many millions of petawatts of energy, some star trek technology like replicators might come true :)
Re:Energy-matter synthesis (Score:4, Informative)
And it's cool to think that, maybe, when you have a warp core that powers a space ship going FTL with many millions of petawatts of energy, some star trek technology like replicators might come true :)
True, but somehow I doubt that anyone will ever be glib while wielding the power of the entire generating output of the Sun, for example (call that 100 billion petawatts). The power at that scale could destroy entire solar systems if a mishap or violent use were to occur.
If you weren't aware of the Kardishev scale [wikipedia.org], you might find it intriguing to consider the implications of a Type II civilization wielding the power of the entire Sun or to think about what a Type III civilization could accomplish.
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Consider this: If the power usage/content of our technology truly scales in the futre as it did from the past to the present then in the future a malfunction in the equivalent of somebody's cellphone today would have the energy to explode like a nuclear weapon. Perhaps there is a flaw in your logic somewhere?
If mankind or it's decendants ever have access to power like this it isn't going to be in the hands of individuals. It will be in the form of massive projects conducted in space far from any lifebeari
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If mankind or it's decendants ever have access to power like this it isn't going to be in the hands of individuals.
I hope you're right. Individuals can't even learn to use apostrophes or spell correctly, let alone manage upcoming energy/mass-conversion-capable smart phones.
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I would think that atomic level manipulation of base materials would be far more efficient than simply trying to convert energy into the desired state of matter.
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That's a really awesome analysis... but I'm an engineer. Any "replicator" that I designed would probably have a water tank, since most food is mostly water. I'd probably have other hoppers full of carbon, oxygen, and hydrogen. The stuff you need to materialize out of light would be a small fraction of the total food: trace elements, vitamins, minerals, etc.
Now if you want it to work with other things besides biomass, well...
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I'm an engineer as well. The "fabricator" approach you describe is much more tenable than an energy-based replicator.
Practically speaking, what would need to be synthesized from energy? Not vitamins (those are organic compounds and you already listed the C, H, and O hoppers, to which I will add N). Technically, you don't even need an H2O tank because you have H and O hoppers. The trace stuff for biomatter is, well, trace. Easy enough to keep those elements around in hoppers as well (I can see the design rev
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Na, all you have to do is slow down the speed of light 100,000 times and you can produce that cup of tea with only 600 watts [google.com].
Yes lets just change a fundamental constant of the universal. Where did I leave that Higgs field manipulator...
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My first thought was 3d printer. Imagine deposing one atom tick layers of any element in any shape. eg; The Star Trek synthesiser.
But that wont happen because they'll ban the thing over irrational fear before the technology reach the point it can print a cup of earl grey.
This technology is self banning thanks to E=MC^2. How many cups of earl grey do you think you can pour out of a single warp core?
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"ok guys all we need is funding for this slab of gold!"
seriously.
Re:Do it, then report it. (Score:5, Informative)
Saying that they're publishing in an attempt to secure funding is the least insightful comment you could possibly make, because that’s precisely how expensive “serious science” gets done: you put your theory up for peer review in a publication like Nature Photonics, and if it’s sound then you go into the contest for funding an experiment. Using your logic we should’ve built the Large Hadron Collider before the theoretical merit in building it was confirmed; if you can’t see why that's a phenomenally stupid way to allocate finite resources then sorry, but I have to doubt you're clever enough to prove a conjecture theoretically, let alone practically.
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No, the matter-from-photon process has very, very low yield.
very old news anyway (Score:2)
Pair production from gamma rays has been observed in bubble chambers for decades. Just the reverse reaction of positron-electron annihilation.