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Scientists find an effective solution for the three-body problem

phys.technion.ac.il

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Re: Scientists find an effective solution for the three-body problem

#111

Post by ksec »

This may be a Rant, or an unpopular opinion.

Life is strange. As if God is reminding me something.

It was only yesterday Overthinking [1] was submitted on HN. A little over 10 years ago many of my friends and colleagues told me to stop overthinking about things. It was causing me some stress and depression because when you start doing analysis many level deep the only conclusion is any small variance will simply cause Chaos. I look it up on the internet and that was the first time I learn about three body problem, Chaos theory, and the much more widely known butterfly effect.

I wish I was taught about this in school or told a lot sooner. To me it is much more about life than it is to maths or physics. Where everything could start out as deterministic, and yet the small difference made end results unpredictable. Over time it also evolved or taught me another concept, many many things or solutions in the world are somehow counter-intuitive.

Then I had a few successful project under my belt, but when I was asked in a Job interview I always attribute to "luck" more than anything else. Which happens to be a word HR and many people hate. Americanism ( which also spreads to non-Americans working inside American companies ) views on the world suggest if you work hard you will get it. I wish that was the case, but there were hundreds if not thousands of known moving parts. And possibly thousands of other unknown unknown. It worked. We worked hard. And it worked. It was everyone involved and lots of luck. I was only a small part of it.

I am sure those who interview me are all pretty smart. May be they should try to solve the three body problem.

[1] https://news.ycombinator.com/item?id=28158435

Re: Scientists find an effective solution for the three-body problem

#112

Post by krisoft »

graderjs wrote: post #95

Fun to watch HN trying to solve the three-body problem in the comment thread.

That’s not what I see. I see people, many of whom are not experts in math or physics, discussing the topic. There are many smart questions, and there are also some which are less so.

Your comment insinuates, but does not state, that this is wrong somehow. If that was your true intention then you are both smug and wrong.

Science is not something you should put in a glass case, only to be handled by ordained priests in the appropriate manner. Asking questions and providing answers to ones best abilities is how it is best interacted with.

If you know better, that is amazing. If you see wrong answers: correct them. If you see misleading questions: explain why they are so. Just don’t be smug, nothing ever got better by that.

Re: Scientists find an effective solution for the three-body problem

#113

Post by DiggyJohnson »

ksec wrote: post #111

This may be a Rant, or an unpopular opinion. Life is strange. As if God is reminding me something. It was only yesterday Overthinking [1] was submitted on HN. A little over 10 years ago many of my friends and colleagues told me to stop overthinking about things. It was causing me some stress and depression because when you start doing analysis many level deep the only conclusion is any small variance will simply caus…

I agree. I’m writing a book about why people play MMORPGs, and you just got at the heart of (part of one of my) theses.

Re: Scientists find an effective solution for the three-body problem

#114

Post by RhysU »

colechristensen wrote: post #26
Aeolun wrote: post #19

Earlier quoted context omitted.

Huh? If this is the case, wouldn’t a 2 body problem also be practically impossible to calculate? I mean, you can certainly still predict to a certain (probably high) level of accuracy, but ultimately that motion is also influenced by factors outside your model.

The question is what happens with a small perturbation and how does it "grow". For a two body problem, you nudge one of the bodies and it is forever off by a small amount, but your predictions into infinity require only a small adjustment to compensate. For a three body problem you nudge one of the bodies and only for a very short time do your previous predictions stay true, the change amplifies until nothing you tho…

This is sometimes called "infinite sensitivity to initial conditions" or "deterministic chaos".

Re: Scientists find an effective solution for the three-body problem

#115

Post by bgroat »

DiggyJohnson wrote: post #113
ksec wrote: post #111

This may be a Rant, or an unpopular opinion. Life is strange. As if God is reminding me something. It was only yesterday Overthinking [1] was submitted on HN. A little over 10 years ago many of my friends and colleagues told me to stop overthinking about things. It was causing me some stress and depression because when you start doing analysis many level deep the only conclusion is any small variance will simply caus…

I agree. I’m writing a book about why people play MMORPGs, and you just got at the heart of (part of one of my) theses.

Is there an email list where I can subscribe for information about this book/pre-order?

Re: Scientists find an effective solution for the three-body problem

#116

Post by [deleted] »

nsizx wrote: post #106
graderjs wrote: post #95

Fun to watch HN trying to solve the three-body problem in the comment thread.

People shouldn't be allowed to ask questions or make uneducated guesses to explore and understand the problem and satisfy their curiosity. We should ask you for permission first.

[deleted]

Re: Scientists find an effective solution for the three-body problem

#117

Post by dekhn »

ko27 wrote: post #41

How good are we at predicting three body movement today with our computers? This is the question I could never find an answer too. Can we do it real time, or few years into the future? Can we do it accurately, to an arbitrary precision? Or is it always fuzzy with statistical outcomes?

we can simulate the solar system to very high accuracy a few hundred years into the future.

https://www.nature.com/articles/nphys728

Re: Scientists find an effective solution for the three-body problem

#118

Post by remram »

thinkski wrote: post #13

When they say motions of three bodies are random and unpredictable, I assume they mean not able to be modeled with a closed form equation? Seems like the motions would still be entirely deterministic — could still predict the locations of the bodies computationally, given your computer computes faster than reality (at least for a reality with only 3 bodies), no?

You can only do that with some error, e.g. your simulation needs some time step that controls the tradeoff between computational resources used and accuracy of the results. For any fixed time step, after enough time your simulation will completely diverge from reality.

Re: Scientists find an effective solution for the three-body problem

#119

Post by graderjs »

krisoft wrote: post #112
graderjs wrote: post #95

Fun to watch HN trying to solve the three-body problem in the comment thread.

That’s not what I see. I see people, many of whom are not experts in math or physics, discussing the topic. There are many smart questions, and there are also some which are less so. Your comment insinuates, but does not state, that this is wrong somehow. If that was your true intention then you are both smug and wrong. Science is not something you should put in a glass case, only to be handled by ordained priests in…

> Asking questions and providing answers to ones best abilities

dude, they're not trying to do that there they're just trying to one up each other. Just like you're trying to do with this comment. It's the hn ape brain mind.

Re: Scientists find an effective solution for the three-body problem

#120

Post by joaorico »

archibaldJ wrote: post #96
lmilcin wrote: post #94

Earlier quoted context omitted.

I am sure that there is at least one mathematician who likes to sit in libraries. But in general there is nothing for a mathematician to do in a library. It is not like you need access to large number of hard to get books. And if you need access to a book, you probably need a lot of time with that book. That is if you even need books at all. Even when I studied theoretical math I wouldn't use books at all. Problems t…

I was looking around but couldn't find the piece my prof sent me 5 years ago. It was a piece from a mathematician's diary about walking and coming up with proofs. There is something about a changing enviroment and being on the move that's very fascinating to me. I guess that one mathematician who likes to sit in libraries probably sits there just for sitting there ;)

Alain Connes, Fields medalist, talks about going on walks while reading math books in a particular way (and on how a mathematician works and should read a book) [0]:

"To understand any subject, above all, a mathematician SHOULD NOT pick up a book and read it.

It is the worst error!

No, a mathematician needs to look in a book, and to read it backwards. Then, he sees the statement of a theorem. And, well, he goes for a walk. And, above all, he does not look at the book.

He says, "How the hell could I prove this?"

He goes for his walk, he takes two hours ... He comes back and he has thought about how he would have proved it. He looks at the book. The proof is 10 pages long. 99% of the proof, pff, doesn't matter.

Tak!, here's the idea!

But this idea, on paper, it looks the same as everything else that is written. But there is a place, where this little thing is written, that will immediately translate in his brain through a complete change of mental image that will make the proof.

So, this is how we operate. Well, at least some of us. Math is not learned in a book, it cannot be read from a book. There is something active about it, tremendously active.

[...]

It's a personal, individual work."

[0] https://www.youtube.com/watch?v=9qlqVEUgdgo

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