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What Is a Particle? (2020)

quantamagazine.org

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Re: What Is a Particle? (2020)

#161

Post by prng2021 »

kayo_20211030 wrote: post #122
prng2021 wrote: post #47

Earlier quoted context omitted.

When you say particles are whatever we say they are, I assume you believe particles are subjective. I'm saying particles are objective, like a "wavelength" as opposed to subjective, like "morals". If you are saying even objective things are whatever we say they are, then this is a useless discussion. Obviously every word is defined with other words and all words are human creations. So yea in that sense, literally ev…

I was saying that I don't know what a particle is, and neither does anyone else, but subjective isn't quite the correct word. What I am sayings is that there are many useful interpretations of what a particle "is" that allows science to progress. The theoreticians and the experimentalists use, sometimes even form, those interpretations to help them along in their work. I'm saying that they yet remain interpretations,…

Is the first law of thermodynamics whatever we say it is? If that's how you want to phrase it, then again, this is a useless discussion. All you're really saying is that the literal English words and sentences we use to define something are human constructs. That's so obviously true.

Re: What Is a Particle? (2020)

#162

Post by antonvs »

lottin wrote: post #125
binary132 wrote: post #61

Earlier quoted context omitted.

I get it but I still think these sorts of concepts are also just another level of mathematical abstraction that isn’t necessarily “really what it is” any more than a rotating ball or a math equation or any of the other ideas are “really what it is”

It's very frustrating. The idea that the universe is made of fields is nonsensical. I don't understand why so many physicists keep saying that.

If you don’t invest the statement “the universe is made of fields” with more meaning than necessary, then it makes more sense.

A quantum field is just a mathematical construct that models an aspect of what can happen at every point in spacetime. The fields follow rules for how they interact, and fluctuations in the fields and interactions between them, according to their respective rules, provide a good model for the universe we observe.

If you consider this purely mathematically, it’s hard to argue with. The models in question make very accurate predictions, can correctly model the vast majority of observations we know how to make, and don’t predict many things that we don’t observe. In other words, all the evidence is that it’s a very good model - a very good fit for the universe we observe.

From this perspective, one way to interpret the statement that “the universe is made of fields” is simply that the universe conforms to the quantum field model. Again, this claim is hard to argue with - it seems to me like a true statement, and there’s a lot of evidence for it.

Hawking & Mlodinow explored this in their description of what they called “model-dependent realism” - see: https://en.wikipedia.org/wiki/Model-dependent_realism

If perspectives like these don’t satisfy you, and you want to try to develop an understanding beyond mathematical models, then you have a tough problem to solve: how to go beyond the models that we know how to construct, to something that somehow gives you some sort of more fundamental insight. But what would that even look like? How would you test it? What would make this approach more true than existing theories?

In short, an answer that satisfies the criteria that you want it to satisfy may simply not be possible.

Re: What Is a Particle? (2020)

#163

Post by Koshkin »

lottin wrote: post #125
binary132 wrote: post #61

Earlier quoted context omitted.

I get it but I still think these sorts of concepts are also just another level of mathematical abstraction that isn’t necessarily “really what it is” any more than a rotating ball or a math equation or any of the other ideas are “really what it is”

It's very frustrating. The idea that the universe is made of fields is nonsensical. I don't understand why so many physicists keep saying that.

"It's very frustrating. The idea that Earth revolves around the Sun is nonsensical. I don't understand why so many astronomers keep saying that."

Re: What Is a Particle? (2020)

#164

Post by Koshkin »

lottin wrote: post #159
jerf wrote: post #153

Earlier quoted context omitted.

Whether or is or it isn't, it does it without consulting you or me or our intuitions. I assume you meant that as an obvious absurdity, but if you were going for that you probably should have avoided the concept of "language", which can be Turing Complete. Still, the main point is, whatever it is, it is, and it isn't asking us for permission to be what it is.

My point is that physical reality cannot be made of something that doesn't exist physically, such as mathematical objects, abstract concepts or more generally ideas of any kind. Do you not agree that this must be true?

It is true, but also kind of trivial. More subtly, one can say that we tend to call what is real using the same words that we use for mathematical objects that model them.

Re: What Is a Particle? (2020)

#165

Post by simpaticoder »

agumonkey wrote: post #146
jakey_bakey wrote: post #143

> "It has been thought of as many things" This makes me remember the time I looked at a random book at my university library, and it happened to be a physics book from 1905. Which was both fascinating and unintentionally hilarious due to it proudly asserting that we knew most of physics now because we knew about atoms, and assuring the plum pudding model as how atoms worked. n.b. Plum Pudding was the old-school idea…

while I often wonder what part of today's knowledge will appear brutally obsolete for those born in the 2100s

As a physics (and SF) enthusiast, I've come to realize that we've discovered most of the physics that exists, and all of what we can use. This is disappointing for those who yearn for FTL or teleportation, but it's good news when you consider that it creates an impregnable defense against interstellar invasion. Within the limits of modern physics, there remains a great deal to understand and apply, especially in QM because to quote Feynman "there's plenty of room at the bottom". Biology and nanotechnology can still revolutionize human existence.

The key problem humans must grapple with an solve, if we are to make it long-term, is how to harness greater and greater power without destroying ourselves. Nuclear destruction has been a very real option for 80 years. Biological weapons could do the job, too. And of course, climate change looms. For many years I agreed with the thinkers that wish for a "backup plan" for humanity; however, I don't think Mars will do it simply because its environment is even harsher than a post-nuclear holocaust Earth. The important reality that THIS is our home, and we must protect her even if it's hard. Yearning for advanced physics to solve all our problems has the unfortunate side-effect of undermining motivation to solve the problems we have now with the tech we have now. It underlies an unfortunate "disposable planet" attitude that we'd be better off without.

Re: What Is a Particle? (2020)

#166

Post by tzs »

scotty79 wrote: post #73
graycat wrote: post #60

Issues: (1) With Itself: Consider Young's double slit experiment: So, have plane with two slits and some distance away a parallel plane with detectors. (A) Several times, shoot a photon at the slit. Observe that the detection locations form parallel lines, i.e., fringes . (B) Cover one slit, repeat, and observe that the detection locations from a smooth hill without fringes. So, from (A) we conclude that the somethin…

You can't detect without affecting. My idea for resolving this is that electron is never a point-like particle. It's always a cloud, just larger or smaller. When it's detected it gets reshaped to be narrower. Mass, energy, momentum and such are a quantities ascribed to the whole cloud and exchanged only on the moment of interaction. Think about diffraction. Photon or electron that passes through a small hole had it's…

> You can't detect without affecting

What about interaction-free measurements, such as in the Elitzur–Vaidman bomb-tester thought experiment [1], which was later shown experimentally to be correct?

[1] https://en.wikipedia.org/wiki/Elitzur%E2%80%93Vaidman_bomb_t...

Re: What Is a Particle? (2020)

#167

Post by travisjungroth »

fasa99 wrote: post #141
travisjungroth wrote: post #133

Earlier quoted context omitted.

One way of viewing it is that math is games. Not in the winner sense, but in the activities with rules sense. Addition is a game. Some games make you better at other activities. Like, playing chess could make you better at logistics because you’re practicing planning and managing losses. Some games match some real world situations so tightly that we can go through them step by step and solve the real world situation…

The idea that it's an abstraction is 100% accurate. That physics is a discrete set of fields with field rules and interaction rules, and what we observe is a scaffold on top of that. It's like okay, let's say the math is right and we have a set of fields, what are they and where are they from, how do we manipulate them. Then the physicists, often driven by ego, is want for an explanation and points to vibrating strin…

So in the viewpoint I’m describing you can definitely call it an abstraction. And abstraction has a vibe of intentionality to it, at least for me. That brings up something I didn’t mention, which is you can make a math game on purpose, to match with something in the real world. You can also make them up for fun (people don’t usually call it “for fun”, but that’s actually a fair label for theoretical mathematics IMO) and then discover the application later.

This is neat! I think it happens less in the physical world, just making up a tool and then finding its application later. It does happen in chemistry.

Re: What Is a Particle? (2020)

#168

Post by itishappy »

lottin wrote: post #125
binary132 wrote: post #61

Earlier quoted context omitted.

I get it but I still think these sorts of concepts are also just another level of mathematical abstraction that isn’t necessarily “really what it is” any more than a rotating ball or a math equation or any of the other ideas are “really what it is”

It's very frustrating. The idea that the universe is made of fields is nonsensical. I don't understand why so many physicists keep saying that.

The magnetic field is one which you've probably had a chance to experience for yourself. Wave a magnet around a magnetic field and you can feel it has a different effect at different points in space. Fields are just time and space varying values for physical properties. Is the universe being composed of magnetism and a few related fields really so nonsensical?

Re: What Is a Particle? (2020)

#169

Post by mock-possum »

hughesjj wrote: post #86
elashri wrote: post #9

Earlier quoted context omitted.

> we often think as though it were dirt, or a billiard ball, or something The problem lies that it is hard to imagine something that does have zero dimensions. You can get the example of ant walking into 2D and it is unaware of third dimension to explain we are have something similar for space-time 4D (although not the same picture exactly as time is different from spatial dimensions). But we don't have an idea how t…

I just think of a zero dimensial object as a ghost. Topological defect. The unpictured thing the contour lines are swirling around. It's influence is only felt by seeing the effects on higher dimensional space, but you can never see the ghost itself.

So more like a poltergeist really

Or a magnet

Re: What Is a Particle? (2020)

#170

Post by mock-possum »

xanderlewis wrote: post #48
elashri wrote: post #9

Earlier quoted context omitted.

> we often think as though it were dirt, or a billiard ball, or something The problem lies that it is hard to imagine something that does have zero dimensions. You can get the example of ant walking into 2D and it is unaware of third dimension to explain we are have something similar for space-time 4D (although not the same picture exactly as time is different from spatial dimensions). But we don't have an idea how t…

> The problem lies that it is hard to imagine something that does have zero dimensions. Do you really think so? It’s not hard to picture the real number line, with the point zero (or any other single point) distinguished. Sure — if you draw it in the standard schematic way you have to give it some area, but it still seems quite intuitive that it’s ‘zero-dimensional’. Especially if you play around with converging sequ…

I do - specifically, it’s hard to imagine a group of things which collectively constitute mass, but individually constitute no mass.

How can something come from nothing?

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