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If you have some grapes and a microwave, it is technically possible to make plasma in the comfort of your home. The catch? It is quite possible that neither the microwave nor the grapes survive the encounter.
For those who do not want to set fire to their kitchens, however, there is good news. First of all, it's not very difficult to reassure your curiosity on YouTube – but more importantly, after decades of speculation, a team of researchers has finally questioned the physics behind this hallucinating phenomenon so you do not have to to do it (please do not do it). Your kitchen and your landlord will thank you.
Here is the deal. In most online iterations, a fearless citizen scientist cuts a grape in half, leaving only a thin connective bridge of the skin, and suppresses the fruit shattered. After a few seconds, the center of the skinned grapes will begin to spew out amorphous, fiery sparks that will ricochet through your microwave. That's it: plumes of heating plasma (by the way, this is probably the point where the reaction must be stopped).
This plasma, of course, is not the plasma of blood, but the state of matter (as in a solid, a liquid, a gas, a plasma) which resembles a gas, but consists of charged atoms, or ionized, whose electrons have been removed. their nuclei positively charged. The result is a swarm of subatomic particles that clash and clash, often emitting blocks of light and heat that may resemble a melting fire.
Plasma is naturally found in lightning, in the Earth's ionosphere and in the solar corona, but can also be artificially generated by exposing a gas to extreme temperatures or an electromagnetic field, which can give it enough energy. 39, energy to emit an electron discharge. their atoms.
So, what activity does plasma bring out of the naked grapes?
The physicist Aaron Slepkov of Trent University in Canada has been a victim of this question for two decades. Slepkov first witnessed the phenomenon by surfing on a website titled "Fun with Grapes" in 1995. But, while videos and blogs on microwavable plasma abounded, it seemed like he There was no rigorous scientific explanation of the physics behind frivolity. Many years later, when Slepkov set up his own research group, he and his trainees, whose author of the study, Hamza Khattak, decided to test some theories. The burned fruits of their work are published today in the journal PNAS.
A myth was quickly broken: a broken grape was not a necessary part of the fire; In fact, the phenomenon was not specific to grapes. The sparks flew very well with intact grapes – as well as with gooseberries, especially cuxomed blueberries, and even stand-alone saltwater pearls – as long as they were two and that # They touched each other.
The key, it seems, is to pile up the energy present in the microwaves in a very small space: the point of contact between the objects in question. In the microwave oven of your garden, the microwaves have a wavelength of about 12.5 cm. But adjacent grapes (which are full of water and can absorb said microwaves) can concentrate energy within a region where the two spheres touch and whose width does not exceed a few millimeters. This creates a very strong and highly condensed electric field at their interface, a pocket of ammunition powerful enough to release negatively charged electrons from naturally occurring salts in grapes and other fruits. And the results are explosive.
A single grape in itself can not do the trick, though. In these cases, the energy is simply concentrated in the center of the grapes. But if they are joined by a consenting dance partner, the "hot spot" of each grape gravitates towards the other, until the two are synergized in a flame of glory.
Pablo Bianucci, a physicist at Concordia University in Canada, explains the author of the study, flexibility, in the microwave to turn into plasma. With microwaves of this wavelength, the typical grapes have an ideal diameter. Scaling a grape – such as a tomato – will not concentrate the energy in a small enough space (for that you must also increase the wavelength). Conversely, a size smaller than the size will prevent the spheres from absorbing enough energy to begin.
"It really shows that there is an explanation for everything," says Lydia Kisley, a physicist and nanoscience expert at Case Western University, who was not involved in the study. "Physics can be used and applied to everyday phenomena. All these theories developed with a pencil and paper can actually be applied to something you throw in your microwave. "
Julie Biteen, a biophysicist and chemist at the University of Michigan, did not participate in the study. Nanophotonics, or the study of light at the nanometer scale, is an example: the wavelengths are condensed in extremely small spaces. Nanophotonics can usually be viewed only with expensive microscopes. But the combination raisin-microwave offers a way to tinker with these phenomena on a larger scale, with affordable household appliances.
Replicating these effects with visible light will require some retouching, explains Bianucci. But it's a logical and exciting step.
In the meantime, it seems that there are finally answers to the mysteries behind the fiery anger of these grapes. It should be noted, however, that the results were not necessarily easy: the publication path was crowded with victims, including a series of fruits of varying sizes and a dozen microwaves, each solemnly baptized with 39, a name honoring his sacrifices. the name of the science (among the fallen microwaves were George I, George II, Jesus, Albert and Thomas). One thing has not changed: plasma is an unstable and dangerous beast, not to be underestimated.
Even Bianucci is reluctant to try this at home. "I'm waiting for my microwave oven to be really out of order," he says.
With the plasma on the photo, "you have to be careful not to melt a hole in the top of your microwave," says Khattak. "I mean you could try, but I would not recommend it. "
For the record, NOVA either.
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