physics stack exchange

Discuss arguments for existence of God and faith in general. Any aspect of any orientation toward religion/spirituality, as long as it is based upon a positive open to other people attitude.

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physics stack exchange

Post by Metacrock » Sat Mar 10, 2018 1:03 pm

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The vacuum is "empty" in every precise sense of the word. What we call "particles" in quantum field theory are states created by so-called annihilation and creation operators, which represent "substracting" and "adding" a particle of a certain type to a state. The free vacuum is by definition precisely the state from which you cannnot substract anything, hence it is "empty". The interacting vacuum is by definition the lowest-lying energy state, but we can't talk about particles for interacting states, so it's meaningless to ask if it is "empty".

The "boiling brew of particles" is a misinterpretationg of what so-called vacuum bubbles mean. They are the Feynman diagrams that contribute to the energy of the interacting vacuum state, and if internal lines of such diagrams described actual particles, then these diagrams would mean a continuous creation and annihilation of particles in the vacuum. But the internal lines of Feynman diagrams are not associated to actual particles states (i.e. no creation/annihilation operator of the free theory belongs to them), so this is nonsense. There are no particles in the vacuum and they don't create a universe.

He is misinterpreting Feynman diagrams to give laymen reading the book a magical and mysterious, but math-free picture of what quantum field theory is about. This picture is almost completely wrong.

It's the lowest-lying energy state of the theory, and the start for so-called perturbation theory. Not much more.
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Re: physics stack exchange

Post by Metacrock » Sat Mar 10, 2018 1:12 pm

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The only way the usual dynamical language for virtual particles is justified by the theory is as purely figurative analogy in ”virtual reality”, useful for informal talk about complicated formulas and for superficial summaries in lectures capturing the imagination of the audience.

This has to be kept in mind when reading in professional scientific publications statements involving virtual particles. Otherwise many statements become completely misleading, inviting a magical view of microphysics and weird speculation, without the slightest support in theory or experiment.
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Re: physics stack exchange

Post by QuantumTroll » Sat Mar 24, 2018 3:51 pm

I don't know if you're trying to make a point here, but that discussion is purely the result of people using English to describe stuff that isn't precisely and completely describable in English. We have these concepts of waves and particles and vacuum and virtual particles and even fields, and they're all approximations of a truth that are more or less inaccurate depending on the conditions you're describing.

You basically have to be a physicist and use mathematical language to not misrepresent what we believe, and even then we know we're not completely right.

I'm not a physicist, and all I can lay claim to is a well-read layman's understanding of the subject matter. I'm at a level where nuclear physicists (I work with some) use their language to speak at me and I know when to nod at the right time to appear as if I follow along, but all I'm really listening for is key words that are relevant to whatever I'm bothering them about (computer stuff).

That said, I can try to check some of your beliefs against my version of weird physics, and maybe that'll be interesting to you. For instance, even the caution against taking "virtual particles" too literally is tricky to interpret, because "virtual particles" are an excellent way of figuring out interaction cross-sections with Feynman diagrams and are crucially important in Hawking radiation, which is pretty mainstream physics by now.

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Re: physics stack exchange

Post by Metacrock » Mon Mar 26, 2018 1:28 pm

You basically have to be a physicist and use mathematical language to not misrepresent what we believe, and even then we know we're not completely right.

I'm not a physicist, and all I can lay claim to is a well-read layman's understanding of the subject matter.
who is "we?"
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Re: physics stack exchange

Post by QuantumTroll » Mon Mar 26, 2018 1:57 pm

Metacrock wrote:
Mon Mar 26, 2018 1:28 pm
You basically have to be a physicist and use mathematical language to not misrepresent what we believe, and even then we know we're not completely right.

I'm not a physicist, and all I can lay claim to is a well-read layman's understanding of the subject matter.
who is "we?"
"We" as in "mainstream physicists", "scientific community", "expert consensus". The uncontroversial bits of science that have an enormous weight of evidence.

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Re: physics stack exchange

Post by Metacrock » Wed Mar 28, 2018 4:30 am

QuantumTroll wrote:
Mon Mar 26, 2018 1:57 pm
Metacrock wrote:
Mon Mar 26, 2018 1:28 pm
You basically have to be a physicist and use mathematical language to not misrepresent what we believe, and even then we know we're not completely right.

I'm not a physicist, and all I can lay claim to is a well-read layman's understanding of the subject matter.
who is "we?"
"We" as in "mainstream physicists", "scientific community", "expert consensus". The uncontroversial bits of science that have an enormous weight of evidence.
you are confused. I am the one who used expert testimony from physicists to back my arguments, you have not, you include yourself in their company after admitting you are not one,but you have pretended no evidence to show I'm wrong ,''I a not even sure you understand what I:"m arguing. Here's a link to my essay please read it:

http://christiancadre.blogspot.com/2018 ... -from.html
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Re: physics stack exchange

Post by QuantumTroll » Wed Mar 28, 2018 5:10 am

Again, I don't actually know what you're trying to say? There's no argument here, just a presentation of what some people have said about the language of physics. edit: never mind, the very last bit of that webpage made it clear.

You're making an argument that, in physics, "something cannot come from nothing", because even in a vacuum there's already "something" there that caused so-called virtual particles to show up?

I agree with that, insofar as virtual particles go. There's fields there (at their lowest energy levels, but they're there because they're probably a property of space-time), and at the very least there's space-time there (or there wouldn't be a "there" to refer to). This has very very little to do with the question you want to discuss, namely the origin of the universe.

Clearly, from a physics standpoint, the Big Bang forms one (and perhaps the only) boundary of the universe. Boundaries are always places where physics follows exceptional rules — waves bounce or refract, time stops, frequencies go to infinity, energy is converted into a two-dimensional manifold, etc . Talking about what happens at low energies in flat space on the inside of a boundary defined by extreme high (infinite?) energy and extremely curved (broken?) space is of course very relevant to the people living here, but tells us a limited amount about the rules that govern that boundary.

As a simulation scientist (I am a physicist in a small way by education), take it from me — boundaries always involve special cases.

The universe is expanding, that much is clear. Space-time can grow. At the universe's ultimate boundary, did it grow from zero or did it grow from something else? Is time linear and causation one-directional at the moment of the Big Bang, as it is now? Is time even a well-defined concept, at that point — is the first moment of time actually a moment of time (because moments of time have moments that came before, right?) or is it something else? And if time itself is a questionable concept, what the fuck can we say about physics and events and what's possible or impossible?

Whatever the case, it has nothing to do with how we talk about virtual particles, which have been and remain a useful concept in physics.

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