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Comment by toxicFork | Hacker News Reader

Going meta here, speaking from the perspective of a software engineer with a great interest for physics.

There are a lot of terms I do not fully understand in this article.

Can you recommend an application that would allow me to select for example the words "distant particles can be correlated in ways that are impossible for classical objects" and find out what lead to that discovery? Or what does "Bell inequality" really mean?

If not, are there recommended methods of understanding articles better?

I am thinking of this process:

- copy the article to a document

- find any words or sentences that you would like to understand better, highlight them in some colour e.g. red

- do some googling / wiki surfing or ask in HN or some kind of forums about them

- add sections after the paragraphs with highlights to explain the words or sentences

- recursion

- once satisfied, highlight the words in a different colour?

View on HN

> what does "Bell inequality" really mean

Some stuff is just hard to understand. You can make analogies, like talking about two people hiding a colored ball in their hand and one of them showing it later, but these are not truly helpful in really understanding the issue. For that you need a bit of math.

One physicist explained this really nicely, saying that because we live in the macroscopic world we have a certain kind of experience of it, and our gut feelings and intuitions are just wrong when applied to the microscopic world, and using math is just a way of avoiding these misconceptions, and after a while of doing that you will get a new "math intuition" of physics.

Our intuitions about macro stuff is really bad, or at least the intuition of people not steeped in Newtonian mechanics is really bad. Gallilean relativity is deeply unintuitive to many physics-naive people, let alone Newtonian mechanics. There's a reason Aristotelian mechanics lasted so long (okay, also the lack of a real scientific method, but still).

To demonstrate, ask a random person these questions:

If I stand on an airplane and jump, do I land where I started, further back, or further forward, relative to the plane?

if I whirl a ball on a string clockwise around my head and let go, does (neglecting vertical motion) the ball travel

A) curving counterclockwise B) curving clockwise C) in a straight line

You'd land slightly back because you'd lose contact with your impeller. I also think most everyone understands how a sling and rock work. Not sure I agree withyour premise. Could you shove a camera in people's face and get dumb answers? Sure. Not sure that's endemic.

You begin at rest, relative to the plane. You jump and experience a force vertically. You land. You haven't experienced any forces horizontally, so you land exactly where you started.

Losing contact with the ground has nothing to do with it. You don't need an "impeller" to continue uniform motion- see Newton's first law.

Maybe I don't understand this thought experiment. Say you are on a plane cruising at 500 mph. The plane is applying constant thrust to counteract atmospheric drag in order to maintain steady 500 mph. At this point your horizontal speed is 500 mph and your vertical speed is zero, as the plane is maintaining level flight. When you decide to jump, you start accelerating towards the ground at roughly 9.8 m/s^2. Your horizontal speed is still close to 500 mph, but it starts decreasing due to atmospheric drag. So you are falling towards the earth, but you are also moving at a considerable horizontal speed relative to the ground due to newton's first law. The plane keeps apply thrust to maintain 500 mph. Eventually you'll land, behind the place but a considerable distance away from where you started.

I may have been imprecise: I'm talking about jumping inside the plane, not wingwalking. There's no drag inside the plane.

If you've ever taken a pee standing up on a plane, you'll notice that your pee doesn't veer rearward. You can juggle balls without losing them (you can try this in the back of a car). If you throw a ball forwards on a plane, it doesn't come back to you, and those carts that are rolled up and down the aisles aren't constantly trying to flee towards the back of the plane.

Well yes, standing inside the plane is a very important distinction. If you are standing inside and decide to jump, there is no atmospheric drag inside the plane to slow down your horizontal speed because any atmosphere in the plane is moving at the same speed you are and so the relative speed is zero.

You might want to read Carlo Rovelli's paper https://arxiv.org/abs/1312.4057.

TL;DR Aristotle's physics lasted a long time because it works in the environment in which people used it.

"If I stand on an airplane and jump, do I land where I started, further back, or further forward, relative to the plane?"

I would say, that most people would answer correctly, that you would not land on the same place, but probably be blown away far backwards from air friction (even though they would just call it wind).

I was imprecise: I'm not talking wing-walkers, I mean standing inside a plane, where wind is hopefully nonexistent

Hm ... and then you expect people would say, they would land backwards? I think allmost everybody would get it right ...

This is based on muddled memories of a highschool physics class, but yes- I'd expect a lot of people to get it wrong, based on the sheer number of my classmates who persistently got it wrong. My teacher subscribed to a slightly nuts teaching philosophy which involved polling the class repeatedly, so I had a pretty good sense of how hard people found the ideas.

Example: literally the other reply to my comment. The notion of an "impeller" to continue uniform motion is Aristotelian, and it seems to coincide with a lot of people's intuition:

https://news.ycombinator.com/item?id=14175605

> The notion of an "impeller" to continue uniform motion is Aristotelian, and it seems to coincide with a lot of people's intuition:

It also coincides with the kinds of experiment that people using Aristotelian physics are in a position to perform. See my comment about Carlo Rovelli's paper.

>Can you recommend an application that would allow me to select for example the words "distant particles can be correlated in ways that are impossible for classical objects" and find out what lead to that discovery? Or what does "Bell inequality" really mean? If not, are there recommended methods of understanding articles better?

Venkman: Ray, pretend for a moment that I don't know anything about metallurgy, engineering, or physics, and just tell me what the hell is going on.

Stantz: You never studied.

(Ghostbusters)

Just studying the principles -- e.g. reading an entry level Physics/QM book, would be better and more solid than surfing around, or asking for opinions on forums (which you couldn't evaluate anyway -- tons of bogus opinions in any kind of forum), or googling stuff.

Stuff like "Bell's inequality" are so basic that merely surfing and skimming wouldn't help (it would be all a kind of concept soup in the end). You can do that with more advanced notions.

Can you recommend an entry level Physics/QM book?

You can also look at some Susskind talks. He is a very good explainer. They don't skim on the math, but it's followable for somebody with a high-school level of math, at least for the basic concepts like spin or bell inequality.

https://www.youtube.com/watch?v=pyX8kQ-JzHI&list=PLQrxduI9Pd...

My first thought: iTunesU, Youtube, etc... there HAS to be tons of videos on "entry level" stuff like this...

Yale Entry Level Physics Class: https://itunes.apple.com/us/itunes-u/physics-video/id3416518...

https://www.youtube.com/results?search_query=Yale+physics

MIT Quantum Physics: https://itunes.apple.com/us/itunes-u/quantum-physics-i/id887...

https://www.youtube.com/results?search_query=mit+quantum+mec...

quick google searches should yield more classes easily enough.

he also did a small book on QM called "the theoretical minimum" IIRC

Definitely _Quantum Mechanics_ by Susskind and Friedman. Only assumes that you are pretty good with probability, and the expositions are nice

The Feynman Lectures on Physics are not half bad.

I'm in the same boat as you, but started looking a while ago when quantum computers started showing promise.

I found:

- PBS Spacetime on YouTube is awesome

- Check out the double split experiment. It seems simple, but when you think about what getting interference patterns when only sending one particle at a time really means..

- Then when ready, the quantum eraser

- Bells inequality is a simple idea that proved the strange interpretation of the double split experiment was true, rather than a more mundane interpretation

If you like the double slit experiment, you'll probably like Feynmann's "motivation" of the path integral in quantum field theory:

Suppose you take the double slit (plate with two holes in it), and you start adding more holes. Of course the particle will go through all of them, but with less probability the further they are off-axis. We can also add more than one plate, and the particle will go through all possible combinations of holes with some probability. Now suppose we let the number of plates go to infinity, and then let the number of holes in each plate go to infinity. The particle still goes through all of the infinite combinations of holes, with less probability if the path is unlikely. But really, there is nothing left anymore between the particle source and the screen! There is just free space! So this path integral with the particle going sort-of-everyhere weighted by probability actually describes propagation through free space.

That connection between slits in the infinite limit and path integrals is really fascinating. I've read of lot of Feynman, but never that. Where does he talk about it?

I'm actually not sure, off the top of my head, but I think it's from his book "Quantum Mechanics and Path Integrals"; he also used it in lectures IIRC.

The two slit experiment has been done with buckyballs, which would indicate all matter is capable of exhibiting quantum nature.

Keep in mind the double slit experiment is designed to illustrate the "effect" we observe, when we observe, is at least partially governed by the observation. Given certain interpretations, it can also have philosophical ramifications[1][2] for the existence of reality, self, and choice.

[1] https://en.wikipedia.org/wiki/Copenhagen_interpretation [2] https://en.wikipedia.org/wiki/Pilot_wave

Do you have a few hundred spare hours? Leonard Susskind did an extensive series of lectures, that assumes some familiarity with Calculus and linear algebra, but almost nothing else.

https://www.youtube.com/watch?v=iJfw6lDlTuA

Highlight and google search? There are already addons that highlight words and provide the definition aka Google Dictionary

Yes it's likely that I'm over-thinking this...

It does not feel good enough since it would be ~opening new tabs and~ make me go through a lot more effort than necessary, and it feels like I would be overwhelmed and give up eventually. If there is something that would make "understanding articles as easy as possible" then that would be amazing. I'll probably end up developing this myself...

Edit: was incorrect about opening new tabs

>It does not feel good enough since it would be ~opening new tabs and~ make me go through a lot more effort than necessary

While you don't need new tabs to google a term with some addons, actual knowledge of the subject, even at a basic level, takes a lot more effort than opening tabs.

There's no magic bullet to learning.

There's no magic to learning. It takes some effort on your part.

I was thinking a Chrome extension to automate this process would be a great way to turn "inaccessible science gibberish" into "Eli5" for a mass of people (I'd like to read that but I'm not willing to do any work other than install a Chrome xtension)

Not sure if that would really work. Understanding science, math, and engineering using analogies leads to misconceptions when one tries to apply them. The math is true understanding. If you understand the equation, then you not only understand the subject, but often what would happen if you tweaked the inputs...etc. Although it would be nice if Wikipedia had an ELI5 section on its physics articles to go through first, so I agree with you there.

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