Can a layman learn GR and QM? REALLY learn?

Factual Questions
1

I frequently see threads here about general relativity, or quantum mechanics, or similar subjects that the general public, other than some new-age poseurs, just accept as being incomprehensible. Intelligent laymen might want to get a dumbed-down answers to a specific question, but they accept that they will never really understand it, and that they are really not even qualified to have an opinion about it. They just defer to the experts.

Yet these same people have no hesitation in arguing passionately about economic policy, or major war strategy, or how God wants us to live.

Well, I’ll leave that second paragraph for another day. My question right now is, is advanced modern physics really beyond an intelligent layman, even if he is willing to put in the time necessary to learn it?

What motivates this is the recent explosion in availability of free online courses. MIT and several other universities have put many of their advanced courses online; some even have all the lectures on video. I expect this trend to increase.

Using myself as an example: I’m retired now. I have a math degree from 30 years ago, and I took a couple semesters of physics, but by thumbing through some modern textbooks, it’s obvious that I’m so rusty that I wouldn’t have much of an advantage over an English major, except maybe that I know I do have some aptitude for math.

So I realize that I am talking about several years of effort. Assuming I spend 3 or 4 hours a day on it, maybe 2 years to get back up to speed in math through diff eq, and freshman physics. Beyond that it will be new stuff, not refresher courses, so it will go slower. Maybe five years to get through the rest of a typical undergrad physics program (obviously I save time by not having to take history or PE concurrently). Maybe seven or eight years after that to get through the required graduate courses in physics.

So that’s about 15 years to get to the point where I would start on my dissertation research, which I assume is also the point where I would be able to read cutting-edge papers on modern physics.

Obviously, most people will not do that. My question is, COULD they? Even if no university in the world would admit me to their graduate physics program if it took me 7 years to get the equivalent of a BS, and wouldn’t keep me if it took me four years to do what they expect to be done in one year of grad school, COULD an intelligent layman with decent but not super mathematical aptitude get through those courses, with a good understanding at their completion, by plodding away at them for as long as it took, or do you really need to be very gifted to get through them at all?

Yeah, I’ll be 65 by the time I get there, but I’ll be 65 even if I just watch TV all day, and other things being equal, I’d rather understand QM and GR when I’m 65, than not. So, can I get there?

2

From many science related threads here on the Dope the opinion of the scientifically minded ones seems to be you really need to understand the math to have a deep understanding of Quantum Mechanics or Relativity.

Needless to say that is graduate level work and then some so a tall order but if you’re game then by all means go for it.

That said I think a decent, if incomplete, understanding can be had by the layman. There are numerous books out there that cover this stuff and are comprehensible without knowing all the math. A deep understanding may not be possible but the broad strokes can be grasped.

Hell, even knowing the math you may be befuddled…

“I think it is safe to say that no one understands Quantum Mechanics.” ~Richard Feynman

“One does not, by knowing all the physical laws as we know them today, immediately obtain an understanding of anything much.” ~Richard Feynman

3

Ahh, what does Feynman know? :stuck_out_tongue:

But yeah, I’m not expecting to know all the secrets of the universe. I’d settle for knowing what other people know, or at least being able to understand what they write about it. Right now, I would be lost on page one of a graduate text, let alone a paper in a journal.

By the way, is that an unreasonable goal? Are PhDs working in, say, GR, able to understand the latest papers on QM, or even on a slightly different aspect of GR, without brushing up on it?

As for the popular books, I don’t say they’re useless, but IMO the level of understanding makes for a significant difference in satisfaction, even when you are talking about stuff from calculus-based freshman physics versus freshman physics for English majors. I just can’t imagine that a book that uses high school math (and some avoid even that) can do much more than state results when it comes to GR or QM.

Not that there’s anything wrong with that, but it’s not what I’m looking for. I want to be able to solve quantitative problems, not just have a general idea of the broad outlines.

4

Einstein himself believed relativity could be grasped by the average guy.
here’s his book:

5

Sure. I doubt understanding an under-grad quantum book will take anywhere close to 15 years, even if you have to learn the “pre-reqs” first.

I think the main thing you’d need is the discipline to work through the problems, as just reading text books probably isn’t enough. But there’s plenty of problems with solution sets out there, so its easily within the reach of a motivated layman.

6

How many problems in this “class” could you (or even an expert for that matter)solve?

And, more importantly, would this lead to a better (for you) understanding of the underlying physics?

7

Maybe I wasn’t clear. I don’t mean solve problems that nobody else has solved, I mean the problems in graduate textbooks.

In the context I intended, it demonstrates an understanding.

8

Thats fine as far as it goes. If thats what you want. The question is is the reward worth the effort?

Let me put it this way. I’ve known physics types that were really good at the math but didn’t seem to really “get the feel” for anything the math was telling them. And, on the opposite end, ones that were pretty terrible at the math, but did have a “good feel” for what the math was telling them (once they ground through the actual math).

9

Solving a problem is very very far away from understanding. In fact the most common advice you hear from people about QM is to not try to understand it, just do the problems and hopefully, maybe, the understanding will come later.

I was doing calculus for years before I really got any of it.

10

Just on this one point - “understand” is not the same as “easily read.” Even a PhD working in GR would take kind of a while to really understand a paper, I think. All physics departments have “reading groups” which get together every week or so to go over recent papers published - and this will be a meeting of graduate students, post-docs, even professors - and try to really understand what they mean and their significance.

The point is physics is hard, even for people who spend their lives doing it, so it’s not likely that you will ever be able to read arxiv with your Sunday coffee and just breeze through the latest in theoretical physics.

I once heard someone say “No one ‘reads’ physics papers. You can ‘read’ Charles Dickens; you can only do battle with a physics paper.”

As for your more general point - I think you absolutely can achieve this if you are dedicated, if you stick to real textbooks used in universities rather than pop-sci drivel, and if you make sure you are always asking questions about stuff you don’t know - maybe online, maybe by corresponding with a physicist. The toughest thing will be the last one; lots of people who try self-learning have trouble with some particular point in general relativity or QM but don’t have anyone to ask, so they conclude there is a deep flaw in the theory and start posting crazy nonsensical crackpotty youtube videos. Don’t become that guy.

11

Like I said, I’ll be 65 (with any luck) whether I learn it or not, and I’d rather learn it. If other people would rather fish or play golf, they have my enthusiastic support.

As for you guys splitting hairs about whether learning to solve problems is really understanding it, that’s fine if you have some alternative path to understanding you would care to share.

But I’ve tried NOT learning to solve problems in QM for the last 50 years, and so far it hasn’t helped my understanding a bit.

12

I was looking for the important points to quote and I decided they are all important. Thanks a lot for your response.

I am optimistic that the online courses will generate discussion groups, hopefully monitored by pros, where I can ask questions. There are also usenet groups like sci.physics, plus a ton of profs who just ad hoc put their lecture notes on the net, so maybe if I see the same thing explained ten different ways, it will get through to me. I guess if all else fails, I can drive 100 miles to the state U and try to find somebody to talk to.

Thanks again.

13

IMO its not even remotely “splitting hairs”. To me it is a fundamental point. Perhaps the most important point there is here. Hey, I ain’t trying to dissuade you or even argue with you. I am bringing up points I hope will make you ask questions to yourself that will help YOU with this quest or if it even makes sense for YOU to do it (or at least do it in the way you suggest).

I’ll throw this out. If you don’t think you’ll enjoy the journey for its own sake, I’d be inclined to say the joy of the destination will not be worth the agony of the trip. Note this is totally different from saying you can or cannot “do it”.

Also note I aint a physics guru at anything so take it all with a big block of salt.

14

I guess I thought it was obvious that it’s something I want to do for its own sake. Even if I don’t reach my goal of PhD-level knowledge, I’ll still know a hell of a lot more about how the universe works than I do now. Just in the last month, starting over on page 1 of a freshman physics text, I’ve learned a lot that I either forgot, or never knew.

I was blessed or cursed, depending on your POV, with the ability to cram for a test and ace it in college. Since I was living in a co-ed dorm with a really spectacular girlfriend, I missed a lot of lectures, and didn’t do much studying until the day or two before the test. I learned enough to ace the tests, but I didn’t retain it for very long.

It’s kind of a revelation to me, now that I’m taking my time and really studying the physics and calc books, how well written some of these books are, and how much I can learn on my own.

Also, how much difference even a little knowledge makes. Yesterday, from chapter 5 of my freshman physics book, I learned how to calculate the minimum angle needed to bank a curve of a given radius so a car going at a given speed will hold the road, even if the surface is icy. I don’t remember being able to do that before – although it must have been in my text 30 years ago, that’s probably one of the lectures I missed. And I have no plans to go into highway engineering, but it’s just COOL to know I can do that, and yes, really understand why it works.

15

Special relativity can be understood by anyone with a high school education and a little bit of intuition for mechanics.

General relativity can be understood by anyone who has five years or so to study metric tensors, differential geometry on curved manifolds, and some pretty hefty vector calculus.

Nobody, including Nobel laureates, understands quantum mechanics. Well, maybe Roger Penrose, but it is equally likely that his Orch-OR microtubes are just crossed.

Don’t let that stop you, though. There is a lot of pleasure in learning the mechanics and the tools that support our understanding of these theories. Even if you are never able to come up with a novel exact solution to the Einstein field equations, just learning the methods gives you a more genuine appreciation for how difficult it is for the real experts to do this, just as learning to read sheet music or study a martial art gives you an enhanced appreciation for composers and champions. It also gives you an excellent set of basic jargon and tools to separate the chaff of pseudo-scientific babble from productive and falsifiable theory.

Stranger

16

I disagree strongly with this. There’s a lot of value in learning the math and being able to do problems. You do gain understanding of the way the world works by understanding the math behind it. To me, “understanding” a system is composed of two main parts: the ability to make predictive statements about its behavior and the ability to confidently prove/check its internal consistency.

The mathematical backing to QM provides both of those. I have little doubt that quantum mechanics gives me an accurate understanding of the workings of the hydrogen atom and its energy levels; to me, that’s all there is. If people want to wonder “Why should the laws of physics be the way they are?” I guess it might be an interesting game, but it’s not really a question of understanding. You never hear people say they don’t understand Newton’s laws of gravity because they don’t know why gravity should exist.

But even more than the fact that QM allows you to more deeply understand the world, it is worth learning simply for its unbelievable beauty. The OP mentions he studied math, so I’m sure he knows what I mean. Quantum mechanics is full of beautiful gems. For me, it was amazing to be able to solve the hydrogen atom. Proving that the energy levels must be what we observe, from first principles, is really tremendously fun and moving, in a “humanity is amazing” sort of way.

17

Is that five years for a PhD-track student, or for a guy doing what I’m doing (3 or 4 hours a day, no tutor)?

And thanks for your remarks on the joy of the journey. Pretty much agrees with my previous post. And I would be very happy if “all” I get out of this is a really good understanding of special relativity, and a good BS detector for GR and QM.

18

That’s sort of what I was thinking, but you said it much better, and with much more authority, than I could have. Thank you.

19

Did I say otherwise?

Can you DO the math or do you GET the math? Or the physics? IME one ain’t the other.

Sure, you need a mix, but if its mostly DO and little GET I don’t think you are going to reach any intellectual Nirvana because you can DO it. Or if you do, its certainly a different one than the getting it one.

20

If I understand you, you are saying that doing the math is necessary, but not sufficient. Conceded.

But you also seem to be disparaging doing the math at all. I don’t get that. What is the alternative?