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Re:Surprising hidden order unites prime numbers and crystal-... by AGoodName on Saturday September 08, 2018 @04:27AM (#17940065)
A brief explanation of why primes peak at repeated multiples from a layman who's wondered why before.

Obvious first example all primes above 2 are of the form 2x+1. An obvious repeating pattern of primes.

You can take this a small step further. All primes above 6 are of the form 6x+1 or 6x+5. Anything else is a multiple of 2 or 3. Above 6 only 1/3 of numbers are worthy of being considered prime. This is a slightly less obvious example.

A small step further - all primes above 30 are of the form 30x+1, 30x+7, 30x+11, 30x+13, 30x+17, 30x+19, 30x+23 or 30x+29. Anything else is a multiple of 2,3 or 5. So above 30 only 8/30 numbers are worthy of being considered prime. See how we've created a new pattern for the multiple of 2x3x5 to rule out a swath of prime candidates..

I could repeat this each prime found. eg. I could take the common multiple of 2,3,5,7 (210) and create a similar pattern for all numbers above 210 that rules out the repeated multiples of 2,3,5 and 7. (leaving us just 58/210 numbers worthy of being considered prime).

This is why you see peaks of primes at various repeating multiples. For every new prime found you can take the multiple of it and all previous primes. From that you can rule out primality for various offsets to any multiples of that number. So primes above certain numbers can only possibly exist in certain forms. Which is why you see primes at repeated patterns from each other - the primes can only exist in those forms.

Re:Surprising hidden order unites prime numbers and crystal-... by chongli on Saturday September 08, 2018 @08:40AM (#17940611)
This pattern forms the basis for wheel factorization [1], a faster way to factor a number than naïve trial division.

[1] https://en.wikipedia.org/wiki/Wheel_factorization

Re:Surprising hidden order unites prime numbers and crystal-... by akira2501 on Saturday September 08, 2018 @03:59PM (#17942456)
Re:Surprising hidden order unites prime numbers and crystal-... by AGoodName on Saturday September 08, 2018 @10:37PM (#17944026)
Author of this thread here. That article states that the above sieve was created in 2003.

I actually wrote and described it back in 2002 - https://forums.overclockers.com.au/threads/show-off.71630/#p...

I didn't think much of it back when i did it and i'm not a mathematician, just a hobbyist. I guess i should publish my prime hobbies more...

Re:Surprising hidden order unites prime numbers and crystal-... by gtt on Sunday September 16, 2018 @05:26PM (#18001236)
Have you though about mailing it to authors of the paper? The should somehow cite you, I guess.
Re:Surprising hidden order unites prime numbers and crystal-... by taneq on Saturday September 08, 2018 @08:20AM (#17940563)
That seems so obvious when you put it like that. (Although I guess all of mathematics is either "obvious" or "unsolved".)
Re:Surprising hidden order unites prime numbers and crystal-... by ipsin on Saturday September 08, 2018 @03:01PM (#17942231)
I think most of what we've solved in math is not obvious.

Some accessible examples would be Fermat's Last Theorem or the four color problem.

Re:Surprising hidden order unites prime numbers and crystal-... by twanvl on Saturday September 08, 2018 @09:00AM (#17940658)
Small correction: there are only 48 (not 58) numbers out of 210 that are not multiples of 2,3,5,7.
Re:Surprising hidden order unites prime numbers and crystal-... by s-shellfish on Saturday September 08, 2018 @10:40AM (#17941001)
I haven't done all the math for this (I've deeply investigated the pattern for 2x+1) but it seems like this would be an obvious and intuitive result of primes. You are still generating primes from primes. Yes, you find more primes, but the computation is still dependent on primes. I'm still of the opinion that there is no complete pattern to the primes.

I'm assuming the researchers do not have the intent of confusing a crystal lattice structure with an actual mathematical lattice, because while they possibly may share similar influences in their models, one is math, the other is physics.

#keepmathpure

Re:Surprising hidden order unites prime numbers and crystal-... by calibas on Saturday September 08, 2018 @12:48PM (#17941602)
I've heard this sentiment before and I don't really understand it. There's no separating physics and math. Keeping math "pure" really means keeping it "purely abstract", so it resists any kind of practical application.
Re:Surprising hidden order unites prime numbers and crystal-... by throwawaymath on Saturday September 08, 2018 @01:40PM (#17941860)
> There's no separating physics and math.

There is. Even though most physics research is extremely mathematical and abstract these days, it's still ostensibly grounded in empirical science. Math is not science, it just provides useful tools and insights for studying science. Unlike physics, the disciplinary imperative of math is not to provide us with truths about this world or any other world. Its imperative is to tell us what must follow as a consequence from a given set of assumptions and definitions. This is a very important philosophical dichotomy because it means that even the most lackadaisical, abstract problems in physics (such as moonshine in high energy physics) are still grounded in something "real." Math need not be grounded to anything real; it can be decoupled from what is real or even possible entirely.

> Keeping math "pure" really means keeping it "purely abstract", so it resists any kind of practical application.

I'm not one to be elitist with regards to pure versus abstract mathematics so I sympathize with your point here. That being said, purely abstract mathematics can be extremely useful even if it doesn't ultimately relate to the real world. Consider what G.H. Hardy wrote nearly a century ago in A Mathematician's Apology:

"...both Gauss and lesser mathematicians may be justified in rejoicing that there is [number theory] at any rate...whose very remoteness from ordinary human activities should keep it gentle and clean."

If only Hardy had lived long enough to see his pure and beautiful number theory sullied with the applications to error-correcting codes and cryptography.

Re:Surprising hidden order unites prime numbers and crystal-... by calibas on Saturday September 08, 2018 @06:38PM (#17943197)
While I certainly understand that math and physics are separate concepts, physics as we know it wouldn't be possible without math. I'm sure in your mind you can separate them, but if you took math away from physics, we wouldn't have modern physics.

Math is how physics is given practical application, if anything, that means science is more abstract than math is.

Re:Surprising hidden order unites prime numbers and crystal-... by s-shellfish on Monday September 10, 2018 @12:40AM (#17949426)
It's about direction of influence.

Physics should not influence math. Math has to be a consequence of it's own axioms, or have it's properties tested against it's own constructions.

Otherwise math falls apart. Then it's useless for physics.

Practical application is wonderful for math. But the direction math is crafted and interpreted matters a lot.

Re:Surprising hidden order unites prime numbers and crystal-... by s-shellfish on Saturday September 08, 2018 @01:20PM (#17941770)
I don't agree with this. And honestly, I really think that depends on what foundation you rely on to think with, work with, create with, test with, and check your own tests with. Physics does not have to use itself to understand itself. Math does.
Re:Surprising hidden order unites prime numbers and crystal-... by Numer on Saturday September 08, 2018 @03:14PM (#17942283)
> Physics does not have to use itself to understand itself.

Could you explain what you mean by that?

Re:Surprising hidden order unites prime numbers and crystal-... by s-shellfish on Sunday September 09, 2018 @09:48AM (#17945859)
It's simple. Physics uses mathematics to construct equations that describe properties of physics.

The difference is physics has reality to test against - observations that can be measured. Math does not have this. Math's only metric against itself is itself.

Re:Surprising hidden order unites prime numbers and crystal-... by sxv on Saturday September 08, 2018 @09:06PM (#17943725)
In your example you started at 1/3 (33.33%) and moved to 58/210 (27.62%). What does this limit approach ad infinitum?
Re:Surprising hidden order unites prime numbers and crystal-... by hiq on Sunday September 09, 2018 @01:23AM (#17944506)