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> Arkani-Hamed, a leader of the effort, called quantum fields “a convenient fiction.” “In physics very often we slip into a mistake of reifying a formalism,” he
by platz 6y ago
> Arkani-Hamed, a leader of the effort, called quantum fields “a convenient fiction.” “In physics very often we slip into a mistake of reifying a formalism,” he said. “We start slipping into the language of saying that it’s the quantum fields that are real, and particles are excitations. We talk about virtual particles, all this stuff — but it doesn’t go click, click, click in anyone’s detector.”
There you go. Anytime someone insists on HN that virtual particles are real, you can just tell them that Arkani-Hamed disagrees with you and that he is also smarter than you.
- pmiller2 6y agoHas anybody ever said they were real? The word "virtual" seems to imply that whoever is using the term should know they are not. They're just convenient mathematical artifacts.
- platz 6y agoI guess you'd be surprised then
- krastanov 6y agoGuilty as charged. I guess I do not see the difference between convenient mathematical artifact and "real". But I am also a Greg Egan fan, so no surprise there. Although people usually do not get hung up on the virtual particles. Rather people get annoyed when we say that the definition of a "particle" is "excitation of a quantum field".
- colordrops 6y agoIt seems the implication is that there is a difference between abstractions and objective reality. But you are not in bad company. Max Tegmark, a physicist at MIT, believes that the fundamental substrate is math, which is just another way of saying that reality is made of mind.
- simonh 6y agoI think that’s getting the cart and the horse back to front. If the fundamental substrate is math then to me that means reality is made of information. I believe mind is a particular form of process on information, but that doesn’t mean all processes on information are minds. This IMHO is the fundamental error at the heart of panpsychism.
- danbmil99 6y agoUpvoted for gratuitous Greg Egan name drop
- xelxebar 6y agoEqual doesn't mean idential. You have an apple in one hand. Since 1 = 1/2 + 1/4 + ... + 1/2^n + ... you therefore have an infinite collection of apple pieces in your hand? Whether that's a useful description, depends on context. Virtual particles are sort of like this decomposition. I think that a lot of confusion arises because of the innocuous seeming equal sign. Explicitly replace the equals by approprate (algebraic) maps, and at least for me, the relationship becomes a lot clearer. Maybe more familiar to HN, maybe it helps to do "typed" math? E.g. counting numbers have a different type than equivalence classes of Cauchy sequences. From a set theory perspective, it makes sense to ask the question whether the number 3 (as a set) equals the collection of triangles in R^3 (as a set). Of course, the two aren't equal, but it seems weird to even ask this question. Maybe it should be just as incongruous to say that some vacuum state equals it's decomposition into virtual particles. The two things are just differently-typed. You need some computation to convert between them.
- sunstone 6y agoNot to muddy the virtual waters here but are the "virtual ephemeral particles" of the vacuum qualitatively different from the "virtual particles" of "electrons and holes" of say semi-conductor physics which are more like mathematical, statistically aggregated entities? Or is the underlying math essentially the same?
- sls 6y agoYou seemingly make a strong, baseless, and unscientific ontological claim, saying that we have one set of mathematical formalisms in our theoretical model that are "really real" and others that are not "really real". Surely the word "virtual" can no more be used to support this claim than the word "imaginary" can be used to distinguish the reality of real and complex numbers.
- jamesrcole 6y ago> Anytime someone insists on HN that virtual particles are real, you can just tell them that Arkani-Hamed disagrees with you and that he is also smarter than you. So, argument from authority then? Are all experts in agreement on virtual particles? If not, which are we meant to 'follow'? And BTW, I have no position on virtual particles.
- _Microft 6y agoArguments from authority are only an issue if the one at the receiving side of them could reason about the topic themselves and are discouraged to actually do that because of the argument.
- jamesrcole 6y agodid you miss the bit where I said: > Are all experts in agreement on virtual particles? If not, which are we meant to 'follow'? ? the person I was responding to picked out one particular expert's view "you can just tell them that Arkani-Hamed disagrees with you and that he is also smarter than you." aside from the silly "he is also smarter than you", just because one expert holds a view doesn't make it right. If all the experts were unanimous, and the particular point had been well tested, then a point like yours would hold. Also, the comment I was responding to was assuming that no-one on HN has a relevant background for having a solid opinion on virtual particles. I certainly don't, but I would not make that assumption about everyone on this forum. I don't agree with the notion that just because someone has a high status in a field that this automatically makes their opinions superior to other people in that field.
- imtringued 6y agoAll "arguments from authority" are breaking these rules. If they didn't, they wouldn't be "arguments from authority". They would be much stronger claims that can stand on their own.
- loopz 6y agoScience is split in two: 1) It is about concrete observations 2) It also hypotheses about potentials. These parts are distinct processes, but also complementary. Both are important for science to be practical and useful. It is always important to be explicit which part of scientific method is under focus, as human minds can only focus one thing at a time. If elements of the universe have probabilistic distributions until observed, you have also a dualism there: 1) the observable element 2) the probabilistic structure surrounding it. Both are mystical and interdependent. Maybe the particle and observation seems more real, but they both adhere to structure that surrounds and shapes them fully too. What we observe though is not particles themselves, but after-effects of the fleeting mirage. So everything is a copy, thus holographic nature.
- firebaze 6y agoNot my field at all so please be forgiving if I mix this up, but aren't virtual particles a possible explanation of the Casimir effect (https://math.ucr.edu/home/baez/physics/Quantum/casimir.html https://math.ucr.edu/home/baez/physics/Quantum/casimir.html)?
- posix_me_less 6y agoThere are different explanations, but the original one (zero-point energy) is very heuristic, involving operations with infinity. There are more physical explanations in terms of physical EM interactions (van der Waals forces), see https://arxiv.org/pdf/hep-th/0503158.pdf https://arxiv.org/pdf/hep-th/0503158.pdf
- raverbashing 6y agoGood, now explain the electron self-energy and the Casimir effect without that
- cjfd 6y agoWhether or not they are real is more a philosophical issue than a physical one. While we should presumably take seriously everything this Arkani-Hamed character has to say on physical issues, on philosophical issues this is much less clear. Everybody can have his/her opinion on these. And since we seem to like to talk out of authority here you can say that a PhD in particle physics told you. I am no longer in that field now anymore, though. So maybe I am indeed more stupid.....
- guerrilla 6y agoThe problem with that is that he's a physicist and not an ontologist, so that's not a partciularly strong appeal to authority.
- 0df8dkdf 6y agowell, physics can be viewed as branch of ontology, I guess everything is a branch of ontology.
- williamdclt 6y agoI'd say that "everything is a branch of physics" is an easier argument to sustain!
- andi999 6y agoFeynman was asked in a seminar why the individual terms of the pertubation expansion have meaning. Basically he cannot fathom the question and his (correct) answer is only the whole sum has a meaning. From 10:00 onwards, quite interesting, https://www.youtube.com/watch?v=72us6pnbEvE&list=PLYuIDo1vZpg3Mwm48ecZJR_i99ThPyo7V&index=1 https://www.youtube.com/watch?v=72us6pnbEvE&list=PLYuIDo1vZp... Of course virtual particles are only present in the individual terms of the pertubation expansion, so their reality is as iffy.