10 hours ago
Our model of the universe is deeply flawed — unless space is actually a 'sticky fluid,' new research hints
https://www.livescience.com/physics-math...arch-hints
INTRO: In a paper that was published on the arXiv preprint server but has not been peer-reviewed, Muhammad Ghulam Khuwajah Khan, a researcher at the Indian Institute of Technology, suggests that space may possess a property called bulk viscosity...
The thing to bear in mind, though, is that the below seems based on a realist stance itself about a theoretical framework (QFT), via the statement "quantum fields exist everywhere". It boils down to a different sub-conception or interpretation grumbling that the other is ontologically bogus. The non-metaphysical justification of it would be the claim that this is the original context that Hawking posited the idea in.
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It’s time to stop teaching the biggest lie about Hawking radiation
https://bigthink.com/starts-with-a-bang/...ally-work/
KEY POINTS: Hawking radiation is one of the most incredible phenomena in the Universe, which will eventually lead to the complete decay and evaporation of the most gravitationally profound objects of all: black holes. According to no less an authority than Stephen Hawking himself, this operates based on particle-antiparticle pairs spontaneously being created by the quantum vacuum, where some members escape, leading to evaporation. But Hawking’s explanation isn’t just misleading, it’s completely incorrect. Black holes don’t emit matter or antimatter via Hawking radiation, but low-energy photons. Here’s how they really evaporate.
EXCERPTS: . . . This oversimplified picture, despite its widespread use, is completely wrong. The idea that the zero-point energy of empty space comes from this “particle-antiparticle popping” is a complete work of fiction. Despite how often this viewpoint has been repeated, and despite the many prominent voices that have lent their support for it, it simply isn’t true. You can’t “pop” a particle-antiparticle pair out of empty space itself, and the Feynman diagrams you see below can’t all actually even exist.
So what is happening, realistically, instead?
There really is what we call zero-point energy, or a value of energy that is inherent to the ground state of any quantum system, and it is often positive and non-zero. But it doesn’t arise from “quantum fluctuations” or “quantum foam” or “particle-antiparticle pair popping” or any other name you give to it. Instead, it comes from what we call the free Hamiltonian (the operator associated with the total energy of a non-interacting system), which represents a series of non-interacting quanta just “sitting there,” oscillating and propagating, but not interacting with any other.
[...] So, let’s recap where we’ve gotten to so far, as background.
[...] All of this, in fact, is precisely what happens for black holes. They emit not Unruh radiation, but rather Hawking radiation, named for physicist Stephen Hawking. It’s fascinating that if you go back to Hawking’s original paper — which celebrates its 50th anniversary this year, by the way — you will find no mention of particle-antiparticle pairs popping in-and-out of the quantum vacuum, as he only invoked that flawed, even wholly incorrect analogy more than a decade later in his popular book: A Brief History of Time. Arguably, it’s one of the most destructive ideas in all of science communication; despite its popularity, it doesn’t represent reality at all. (You can read this older piece for an instructive takedown of the idea.)
And yet, it’s wholly unnecessary. Perhaps the only big arguments left over Hawking radiation are:
But what doesn’t happen is what you most commonly see illustrated: particle-antiparticle pairs, where one member of that pair escapes and carries energy away. After all, Hawking radiation isn’t made up of either particles or antiparticles or a mix of them; it’s practically exclusively photons, or quanta of massless radiation, just as names like “Unruh radiation” or “Hawking radiation” would imply.
Instead of succumbing to this misconception and propagating it further, however, we can fight against it with correct information. After all, why shouldn’t we use the same line of thought that actually led Hawking to his correct derivation of the radiation that bears his name, rather than the woefully incorrect analogy he put forth years later: where he introduced a misconception that would go on to misinform the field for 50+ years to come? (MORE - missing details)
https://www.livescience.com/physics-math...arch-hints
INTRO: In a paper that was published on the arXiv preprint server but has not been peer-reviewed, Muhammad Ghulam Khuwajah Khan, a researcher at the Indian Institute of Technology, suggests that space may possess a property called bulk viscosity...
The thing to bear in mind, though, is that the below seems based on a realist stance itself about a theoretical framework (QFT), via the statement "quantum fields exist everywhere". It boils down to a different sub-conception or interpretation grumbling that the other is ontologically bogus. The non-metaphysical justification of it would be the claim that this is the original context that Hawking posited the idea in.
- - - - - - - - - - - - - -
It’s time to stop teaching the biggest lie about Hawking radiation
https://bigthink.com/starts-with-a-bang/...ally-work/
KEY POINTS: Hawking radiation is one of the most incredible phenomena in the Universe, which will eventually lead to the complete decay and evaporation of the most gravitationally profound objects of all: black holes. According to no less an authority than Stephen Hawking himself, this operates based on particle-antiparticle pairs spontaneously being created by the quantum vacuum, where some members escape, leading to evaporation. But Hawking’s explanation isn’t just misleading, it’s completely incorrect. Black holes don’t emit matter or antimatter via Hawking radiation, but low-energy photons. Here’s how they really evaporate.
EXCERPTS: . . . This oversimplified picture, despite its widespread use, is completely wrong. The idea that the zero-point energy of empty space comes from this “particle-antiparticle popping” is a complete work of fiction. Despite how often this viewpoint has been repeated, and despite the many prominent voices that have lent their support for it, it simply isn’t true. You can’t “pop” a particle-antiparticle pair out of empty space itself, and the Feynman diagrams you see below can’t all actually even exist.
So what is happening, realistically, instead?
There really is what we call zero-point energy, or a value of energy that is inherent to the ground state of any quantum system, and it is often positive and non-zero. But it doesn’t arise from “quantum fluctuations” or “quantum foam” or “particle-antiparticle pair popping” or any other name you give to it. Instead, it comes from what we call the free Hamiltonian (the operator associated with the total energy of a non-interacting system), which represents a series of non-interacting quanta just “sitting there,” oscillating and propagating, but not interacting with any other.
[...] So, let’s recap where we’ve gotten to so far, as background.
- Empty space isn’t empty, but possesses quantum fields everywhere.
- We shouldn’t view these quantum fields as “particle-antiparticle pairs popping in-and-out of existence,” which is a false temptation, but rather as an ensemble of non-interacting particles in the ground state.
- If you are stationary and not accelerating in flat, empty space where these quantum fields exist, you will see the vacuum as corresponding to this ground state, and you will see no radiation emerging from anywhere.
- But if you are uniformly accelerating, even through flat, empty space, you will effectively “boost” the energy of the ground state, and that will lead to a thermal bath of radiation.
[...] All of this, in fact, is precisely what happens for black holes. They emit not Unruh radiation, but rather Hawking radiation, named for physicist Stephen Hawking. It’s fascinating that if you go back to Hawking’s original paper — which celebrates its 50th anniversary this year, by the way — you will find no mention of particle-antiparticle pairs popping in-and-out of the quantum vacuum, as he only invoked that flawed, even wholly incorrect analogy more than a decade later in his popular book: A Brief History of Time. Arguably, it’s one of the most destructive ideas in all of science communication; despite its popularity, it doesn’t represent reality at all. (You can read this older piece for an instructive takedown of the idea.)
And yet, it’s wholly unnecessary. Perhaps the only big arguments left over Hawking radiation are:
- whether we’ll ever be able to measure it,
- and whether it requires an event horizon to truly exist, or whether all masses create it,
But what doesn’t happen is what you most commonly see illustrated: particle-antiparticle pairs, where one member of that pair escapes and carries energy away. After all, Hawking radiation isn’t made up of either particles or antiparticles or a mix of them; it’s practically exclusively photons, or quanta of massless radiation, just as names like “Unruh radiation” or “Hawking radiation” would imply.
Instead of succumbing to this misconception and propagating it further, however, we can fight against it with correct information. After all, why shouldn’t we use the same line of thought that actually led Hawking to his correct derivation of the radiation that bears his name, rather than the woefully incorrect analogy he put forth years later: where he introduced a misconception that would go on to misinform the field for 50+ years to come? (MORE - missing details)