How many people understand general relativity?

purpledog

Newcomer
How many people on earth really have an intuition of general relativity?

Or another way of looking at it: how many people read "Relativity: The Special and General Theory" (like me) and did understand the second half (unlike me)?
 
i go as far as understanding reference frames and ping pong balls on trains. anything to do with aproaching the speed of light's effects i don't intuitively understand.
 
How many people on earth really have an intuition of general relativity?

Or another way of looking at it: how many people read "Relativity: The Special and General Theory" (like me) and did understand the second half (unlike me)?
Depends upon what you mean by "understand". If you mean, "Can do the math," then the answer would be a large portion of physicists working in the Astrophysics and Cosmology areas, as well as a few other theorists and mathematicians. If you mean, "Understands on an intuitive level," then that would be precisely nobody. It's impossible for us to understand GR at any sort of intuitive level, just as it's impossible for us to understand quantum mechanics on any sort of intuitive level.
 
It depends also what you mean by intuition.

Many of us who have worked with a theory sufficiently long that we end up with certain expectations of what the correct answer for a given physical problem is, without looking at the math. The intution in that case is still mathematical, but in many ways its still the same thing.

As for being able to visualize dimensions >3. Well, that too is a little weird, and can depend what you mean. There have been famous mathematicians/topologists in the past who have uncanny abilities to 'see' 3 dimensional embedded cross sections of higher dimensional surfaces.

There have also been many cases where certain people can 'visualize' the correct answer (say in complicated d>3 scenarios with knots) without being able to prove it, or even motivate it mathematically.
 
A high percentage of the population would understand this intuitively only if it somehow affects natural selection, and the reproductive rates of highly intelligent folks. Right now, about half of the US population still believes fairy tales involving talking snakes and jewish zombies...so in my opinion we're headed the exact opposite direction. Oh yeah, remember who is breeding like crazy...yep it's the religious folks. Somehow we have to make awkward, lanky, bookworms ultra sexy and get them laid as much as possible. now, where did I put my pocket protector??
 
I think I uderstand most parts of it, more or less. But not at the same time. Multiple effects don't overlap. And the math is beyond me (I really should study it some time). So I probably get most of it wrong.
 
Depends upon what you mean by "understand". If you mean, "Can do the math," then the answer would be a large portion of physicists working in the Astrophysics and Cosmology areas, as well as a few other theorists and mathematicians. If you mean, "Understands on an intuitive level," then that would be precisely nobody. It's impossible for us to understand GR at any sort of intuitive level, just as it's impossible for us to understand quantum mechanics on any sort of intuitive level.

I thought Einstein got it using intuition only as he was not such a clever mathematician.

Yet maybe that was some sort of mathematics intuition and not something purely out of "common sense".

But then one might argue that math are the language of the world, especially for scientist. So maybe he did really get an understanding of it...

As for quantum stuff, well, that's the other thing on my todo list ;)
 
There have also been many cases where certain people can 'visualize' the correct answer (say in complicated d>3 scenarios with knots) without being able to prove it, or even motivate it mathematically.

Also, maybe one can try to understand GR in a 2d world, even a 1d world.

For instance, the thing with the universe being cyclic can be understand in a 2d world: we are on a sphere, but on a very very small portion of it. So we think it's a plane. But if you go straight, you end up in the same initial place.

That's a stupid example, but maybe there's more to do along that line...
Also, I always have this dream of making a GR realtime rendering engine where the speed of light would just be a parameter...

Visualization basically
 
btw, understanding is relative, fair enough, but the question is "How many people on earth really have an intuition of general relativity?"

So far, one answer by Chalnoth: 0
Maybe an answer by Frank: 1 ;)
 
The "intuition" that he used came in the form of the assumptions used to approach the theory, not in interpreting how it applies to real, physical situations. As a theorist, Einstein had a particular idea about what makes for a "beautiful" theory. His primary idea, as it relates to General Relativity, is as follows:

1. All physical laws must be completely independent of the observer's frame of reference.
2. Gravity is equivalent to acceleration.

Through these basic assumptions, and with a lot of frustrating work and some help from mathematicians, he came up with General Relativity. If he had an "intuitive" understanding of the theory, after all, it wouldn't have taken him more than ten years to develop the theory after he published his Special Theory of Relativity in 1905. It is, after all, no more than an extension of the special theory. It's just a difficult one. He said, in short, "I think the world must behave in this way. Now to do the hard work and figure out precisely what that means."

This is the way that theory progresses. A scientist has a general intuition that making use of particular sorts of rules makes for more beautiful mathematics. Different scientists have different ideas for what makes for the better rules. Some get lucky.

We might argue, of course, that those that end up being correct don't get lucky, but instead are applying some deep physical intuition. I just don't think there's much evidence to support that hypothesis, as at any given time there often seem to be many valid approaches to an unsolved problem. Though having that intuition may help narrow the playing field, it won't narrow you in on the precise theory.
 
Depends upon what you mean by "understand". If you mean, "Can do the math," then the answer would be a large portion of physicists working in the Astrophysics and Cosmology areas, as well as a few other theorists and mathematicians. If you mean, "Understands on an intuitive level," then that would be precisely nobody. It's impossible for us to understand GR at any sort of intuitive level, just as it's impossible for us to understand quantum mechanics on any sort of intuitive level.

If you're working on that kind of definition of intuition (ie the literal dictionary one) then next to nothing can be understood at any sort of intuitive level.

If the question is more is it possible to understand special/general relativity on a subconsious level then certainly, at least to some, certainly as possible as it is for individuals to gain a subconsious understanding of newtonian mechanics, all it takes is the right individual and experience, even if its just theoretical examples rather than practical ones.
 
If you're working on that kind of definition of intuition (ie the literal dictionary one) then next to nothing can be understood at any sort of intuitive level.
Right, that's exactly the case. And I think it is extremely important to highlight this because of the following.

The idea that we are capable of a deep, intuitive understanding of reality that lies beyond what our brains evolved to learn can be exceedingly misleading. It leads to all sorts of pseudo-scientific crap that leads people to believe that because a scientific theory seems weird, it must therefore be wrong. It leads all sorts of people to believe that, say, quantum mechanics is incorrect, or that Special/General relativity must be wrong, or any number of other such things.

It is exactly the case that these theories run extremely contrary to our "common sense", but this shouldn't be in any way surprising, as our "common sense" is built up from our evolutionary past and everyday experience. These theories, however, describe things that are vastly outside of either our evolutionary past or everyday experience. So we should expect that they end up being extremely disturbing on some level.

Can people who have worked with a theory like General Relativity get a good enough grasp of the mathematics to often pick out an answer before sitting down and solving it? Certainly! But if they want to be sure, they still have to sit down and actually work it out. Even the most experienced will be wrong on occasion, after all.
 
Can people who have worked with a theory like General Relativity get a good enough grasp of the mathematics to often pick out an answer before sitting down and solving it? Certainly! But if they want to be sure, they still have to sit down and actually work it out. Even the most experienced will be wrong on occasion, after all.


but the same could be said for a simple case of newtonian mechanics. The most experienced snooker player still cocks it up occasionally and not just because he miscued.
 
Newtonian mechanics is a good example of what we can mean by intution.

Consider the 4 body gravitational problem. Despite knowing the math since time immemorial, and having seen it in action, I still have absolutely no idea how the system will evolve given a set of initial conditions. I'd need a computer to do it for me, since the numerical calculation itself would probably lead me to making an error. I could make a guess, but it would be hopelessly naive.

However, some people can 'visualize' it pretty accuratedly, or at least much more accuratedly than I can. Some of it has to do with familiarity with the problem but sometimes the brain can make intuitive leaps that are hard to explain. A good pool player for instance, probably has more intution than most physicists do =)
 
but the same could be said for a simple case of newtonian mechanics. The most experienced snooker player still cocks it up occasionally and not just because he miscued.
Yes, precisely. Even with basic Newtonian Mechanics many solutions are, on their face, counter-intuitive. A good example is angular momentum, which does not seem to behave as we would naively expect.
 
Yes, precisely. Even with basic Newtonian Mechanics many solutions are, on their face, counter-intuitive. A good example is angular momentum, which does not seem to behave as we would naively expect.


Meaning that there's no reason for general/special relativity to be out of bounds for 'intuitive' solutions.

The only reason basic newtonian mechanics is 'intuitive' to many people is because it's picked up when you're a baby/child but you didn't start off with it inbuilt into your brain, the results of everything are 'counter-intuitive' to a baby, bar feeding, crapping and sleeping anyway, babies are routinely fascinated by things we all take for granted.

Take your example of angular momentum there. My first thought to that was "it doesn't?", becuase to me, it does, but then I spent a (probably disturbingly) large amount of time spinning things in my childhood ever since I was capable of spinning something.

Obviously the rates of learning vary hugely between people, but they all learnt it, no one is born truely intuitive, some just apparently paid alot more attention when growing up, and some are better at making extrapolations from previous experiences (which is essentially what 'gut feeling' is) but theres no reason why something new cannot be added to that. Even in adulthood the brain is able to 'rewire' itself.

If it couldn't, well we would all be pretty useless at a video game that didn't follow physics as per reality (ie all of them, particularly the old ones).
 
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