Physicists Use Bubbling Quantum Vacuum To Hopscotch Heat Across Empty Space (livescience.com) 23
Long-time Slashdot reader fahrbot-bot quotes Live Science:
When you touch a hot surface, you're feeling movement. If you press your hand against a mug of tea, warmth spreads through your fingers. That's the sensation of billions of atoms banging together. Tiny vibrations carry thermal energy from the water to the mug and then into your skin as one molecule knocks into the next, sending it careening into a third -- and so on down the line.
Heat can also cross space as waves of radiation, but without radiation, it needs stuff to pass through -- molecules to bang into other molecules. Vacuums have no 'stuff' in them, so they tend to trap heat. In Earth's orbit, for example, one of the biggest engineering challenges is figuring out how to cool down a rocket ship.
But now, researchers have shown that, on microscopic scales, this isn't really true. In a new paper published Dec. 11 in the journal Nature, physicists showed that little vibrations of heat can cross hundreds of nanometers of empty space. Their experiment exploited an uncanny feature of the quantum vacuum: It isn't really empty at all.
Heat can also cross space as waves of radiation, but without radiation, it needs stuff to pass through -- molecules to bang into other molecules. Vacuums have no 'stuff' in them, so they tend to trap heat. In Earth's orbit, for example, one of the biggest engineering challenges is figuring out how to cool down a rocket ship.
But now, researchers have shown that, on microscopic scales, this isn't really true. In a new paper published Dec. 11 in the journal Nature, physicists showed that little vibrations of heat can cross hundreds of nanometers of empty space. Their experiment exploited an uncanny feature of the quantum vacuum: It isn't really empty at all.
What (Score:2)
Quick explanation (Score:5, Informative)
Quick explanation
One of the interpretations of quantum mechanics is that space is a seething "foam" of quantum particles that come into existence and blip out of existence before any conservation laws are broken. Literally, pairs of particles are formed - breaking conservation of energy - and recombine so quickly that the conservation break falls within the uncertainty principle timing of the event.
Lots of particle actions can be described by a real particle interacting with one of these virtual particles, in a way that kicks it out of the space or timing of the uncertainty principle and turning it from a virtual particle to a real particle.
These particles are considered virtual, because they cannot be directly measured.
Heat travels by conduction (and radiation and convection), but in space there's nothing to conduct to. Because of this spacecraft have problems dissipating extra heat and so on.
The paper has demonstrated that the quantum foam can be used to conduct heat across a small gap, using the virtual particles in the manner of real particles. This confirms a recent theoretical prediction of the effect.
Re: (Score:2)
Quick explanation
One of the interpretations of quantum mechanics is that space is a seething "foam" of quantum particles that come into existence and blip out of existence before any conservation laws are broken. Literally, pairs of particles are formed - breaking conservation of energy - and recombine so quickly that the conservation break falls within the uncertainty principle timing of the event.
Lots of particle actions can be described by a real particle interacting with one of these virtual particles, in a way that kicks it out of the space or timing of the uncertainty principle and turning it from a virtual particle to a real particle.
These particles are considered virtual, because they cannot be directly measured.
Heat travels by conduction (and radiation and convection), but in space there's nothing to conduct to. Because of this spacecraft have problems dissipating extra heat and so on.
The paper has demonstrated that the quantum foam can be used to conduct heat across a small gap, using the virtual particles in the manner of real particles. This confirms a recent theoretical prediction of the effect.
You seem knowledgeable on the subject, why just a small gap?
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And to follow that up , this virtual "quantum foam" that cannot be measured, wouldn't this be a way to measure?
You pass current through a wire and you can reliably measure the material or gauge by what you get to the other side.
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Cannot be directly measured. Indirectly is easier.
Interesting , I always considered the reading on a multimeter to be a direct measurement. But I guess maybe it isn't.
What would be the direct measurement equivalent to the reading on an ohmmeter?
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I think the "small gap" is because it has to happen quickly enough that it can be justified by uncertainty. And light move pretty fast, so that's not much time.
Once upon a time I could have given you a better answer, but quantum physics is multiple decades ago for me, and the details have slipped away. But the equations did work out when I checked them.
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You seem knowledgeable on the subject, why just a small gap?
If I had to guess, Planck time [physlink.com]. Anything larger and there would be too much time between the creation and blipping out of the particles which would leave too much space between the virtual particles for the process to take place.
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pairs of particles are formed - breaking conservation of energy - and recombine so quickly that the conservation break falls within the uncertainty principle timing of the event
Quantum mechanics allows the kinetic energy of a virtual particle to be negative, [wikipedia.org] a more appealing explanation that handwaving about extremely short particle lifetimes.
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The term "quantum foam" is typically used in speculative theories about quantum gravity, but this is completely unrelated to this topic. The term you want to use is quantum field. (Real) particles are excitations of quantum fields. The vacuum state of a quantum field has no excitations but still it has a complicated structure. This complicated vacuum state is sometime described as fluctuations of virtual particles. But virtual particles are a concept which should *not* be taken too literal. All popular ex
Not to me. (Score:2)
As a regular PBS SpaceTime viewer (on YouTube), this was a perfectly straightforward headline.
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It made perfect sense to me. What's the difference? I sometimes look things up in Wikpedia? I more or less pay attention to developments in physics, as any self respecting technology geek ought to?
Nothing new (Score:1)
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did they know the difference between principle and principal?
cuz u don't
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No. They spoke Greek. (Well, depending on which group he meant. It could have been Latin. But the original ones were Greek.)
Indeed (Score:2)
"When you touch a hot surface, you're feeling movement."
Indeed, I feel my lips move and yelling 'Holy flying fuck is that hot!'
Re: Quantum vacuum creates spacetime emergent prop (Score:2)
What happens in superfluid vacuum when it has inhomogenous movement? A superfluid can have vortexes, so why not vacuum? What happens when it moves near lightspeed?
Do you mean pilot wave theory? (Score:2)
Because from the PBS SpaceTime video, that one looks pretty bad to me. Not bad in a "bad idea" sense. But in a "chances of it being right, when compared to real world observation" way.
Of not, then nevermind.
Aristotle was right... (Score:2)
Aristotle may have been right all along: nature abhors a vacuum.
Also, if phonons can pass through its, it's not really a vacuum.
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Aristotle may have been right all along: nature abhors a vacuum.
Right, nature abhors a vacuum so intensely that it spends much of its time posting to social media sites and writing shocked and appalled emails to editors of scientific journals.
Vacuums have no 'stuff' in them.. right.. (Score:2)