[evan_au]

physics was initially described very successfully via mathematics

I have seen the section from Galileo's notebook where he determined that the velocity of a particle increases as time squared. He used an apparatus similar to the frets on a musical instrument fastened across an angled track, with a metal ball falling under gravity.

The commentators pointed to the section where he recorded his measurements.
- Galileo had crossed out some of the results and written in other numbers to make them fit the maths
- Because he realised that when the ball was moving slowly, the frets presented a significant obstruction to the ball, which wasn't a problem when the ball was moving quickly.

Pure physics might be describable by pure maths, but the complexities of the real world are far too complex for pure maths. That's why we have a field of "applied maths". Both areas of maths use computers extensively, as do pure and applied physicists.

(computer science) uptake by the physics community appears to have been very limited to date

Most of the very biggest supercomputers in the world are for physics problems, including predicting the weather, and designing atomic bombs. But let's look at some others:
- A simulation of the entire universe since the Big Bang, comparing the distribution of galaxies to what we see today. The Illustris project used 19 million CPU hours:

- A simulation of the last few hours of a star's life as it undergoes a supernova. The first successful simulation (published early 2019) took 6 months CPU time on a large supercomputer.

- The Square Kilometer Array, beginning construction in Australia and South Africa will have a supercompter more powerful than any currently on Earth.

[mxplxxx (OP)]

A simulation of the entire universe since the Big Bang, comparing the distribution of galaxies to what we see today.

I would love to see the code behind this. Or even a description of what the code does. Given we don't actually know what happened at the time of the Big Bang, I am skeptical that such a simulation could exist.

I would not class anything as  a simulation that does not simulate something. The use of mathematics is rarely a simulation of what has actually occurred. The fact is we don't actually know what has occurred in the evolution of most physics systems. In other words we can predict many results but we have no idea how they occurred. Therefore we cannot simulate them.

In any case I have said simulations in physics are few and far between and, even when available, the code behind them is rarely available. I suspect that very few physicists can program a reactive system or understand the workings of a hierarchical finite state machine which would be the minimum required computer science expertise required for a physics simulation.

[mxplxxx (OP)]

The first successful simulation (published early 2019) took 6 months CPU time on a large supercomputer.

Not sure what kind of a simulation this was, given we don't actually know what happens inside a super nova (admitted by scientist in the video who also admitted that gravity always won out in simulations attempted to date).

[jeffreyH]

A simulation of the entire universe since the Big Bang, comparing the distribution of galaxies to what we see today.

I would love to see the code behind this. Or even a description of what the code does. Given we don't actually know what happened at the time of the Big Bang, I am skeptical that such a simulation could exist.

I would not class anything as  a simulation that does not simulate something. The use of mathematics is rarely a simulation of what has actually occurred. The fact is we don't actually know what has occurred in the evolution of most physics systems. In other words we can predict many results but we have no idea how they occurred. Therefore we cannot simulate them.

In any case I have said simulations in physics are few and far between and, even when available, the code behind them is rarely available. I suspect that very few physicists can program a reactive system or understand the workings of a hierarchical finite state machine which would be the minimum required computer science expertise required for a physics simulation.

How dismissive and pompous of you. Well done! Of course only you could be smart enough for such achievements.

Scientists, the best ones, are often much more intelligent and inventive than you will ever give them credit for. They have to be. Try finding an exact solution to Einstein's field equations.

Try to start listening and get off your soap box.

[jeffreyH]

LDA #0
:LOOP
ADDA #1
CMPA INFINITY
JNE LOOP

That looks like mathematics to me.

[Bored chemist]

I'm going to get lynched for this but...

I suspect that very few physicists can program a reactive system or understand the workings of a hierarchical finite state machine which would be the minimum required computer science expertise required for a physics simulation.

Many physicists will also delegate the mundane work of repairing a faulty car engine to someone who can't do the physics, but is "good with their hands".
In much the same way, they will delegate writing code.
Did you know that the phrase "code monkeys" is fairly commonly used?
https://en.wikipedia.org/wiki/Code_monkey

The fact is that most scientists (at least those who, like me were teenagers in the 80s) are able to write code.
Some of us still do.

So here's the dissymmetry for you.
Physicists can (almost always)  programme.
Programmers  (almost always) can't understand physics.

You have demonstrated that you can't

[mxplxxx (OP)]

How dismissive and pompous of you. Well done! Of course only you could be smart enough for such achievements.

And your statement is not dismissive and pompous + sarcastic:) ? I think you may be confusing impact and intent?

I try and state facts and keep emotion out of my posts. I have an applied psychology degree from the Australia College of Applied Psychology (can post the certificate if necessary). I have no need to be dismissive and pompous. I would really like you guys to criticize what I say rather than what sort of a person you think I am. Use this as a rule to live by and life suddenly becomes much easier:).

If I am pressing a button you would rather not have pressed, maybe there is a lesson involved for you (or maybe I am just plain wrong, in which case tell me what you think is wrong and why and give me an alternative if one exists).

[mxplxxx (OP)]

Physicists can (almost always)  programme.
Programmers  (almost always) can't understand physics.

What is your basis for these statements?

 I am a full stack software developer. I design all aspects of an App as well as doing the programming, solo. The difference between me and a developer who cuts code is enormous. I have university maths to HD standard.  I am amongst the elite of my profession. A physicist who desires his theory to be simulated would explain the theory to me and I would do the rest. Unless, of course, the physicist is also a pretty smart software developer. 

Many computer programs are amongst the most complex entities in existence. Creating them requires someone with considerable simplification, improving, explaining and creating skills. Is this typical of physicists? It certainly is of top software developers.

[mxplxxx (OP)]

In much the same way, they will delegate writing code.
Did you know that the phrase "code monkeys" is fairly commonly used?
https://en.wikipedia.org/wiki/Code_monkey

From Urban Dictionary:

code monkey

One who copies all code from other sources and prays that their code compiles. Normally used in a negative manner when used by more experienced programmers.

If you are trusting code monkeys to write your programs, you will be skating on very thin ice:). For something like a physics simulation, either do it yourself if you are good enough or assign it to a rock-star Software Developer with a physics bent (like me:)).

[Bored chemist]

Physicists can (almost always)  programme.
Programmers  (almost always) can't understand physics.

What is your basis for these statements?

Well, let's start with the second.
You are a perfect example.
A programmer who doesn't understand physics (if you did, you wouldn't have started this thread).
And, while, strictly, I'm a chemist, rather than a physicist, I do get paid to write code.

So, based on  a rather small sample size, I'm right.

For something like a physics simulation, either do it yourself if you are good enough or assign it to a rock-star Software Developer with a physics bent (like me:)).

No.
If I wanted someone to code physics for me I'd certainly not choose someone who, like you, doesn't even understand how we measure photon energies- even after being repeatedly  told how we do it.

You make the monkey look good.

[mxplxxx (OP)]

LDA #0
:LOOP
ADDA #1
CMPA INFINITY
JNE LOOP

That looks like mathematics to me.

It looks like a snippet of Assembler code containing some maths to me.  What is your point?

[mxplxxx (OP)]

Getting back to the topic, I am going to postulate an explanation of how a photon behaves like an EM wave and the process involved in transferring the photon's energy to another particle.

Most (possibly all) objects in the universe are systems. A system consists of a central (centre of gravity) object surrounded by peripheral system objects. So we have a solar system containing a central Sun object surrounded by peripheral planetary system objects such as the Earth system. There exist very similar bosonic and fermionic systems. A bosonic system has a central object of that can assume a single state only. A fermionic system has a central object that can assume multiple states. A bosonic system is basically related to events whilst a fermionic system is related  to data.
The system/central object relationship may correspond to the wave/particle duality relationship in physics.

It would also seem that inner and outer shells are present. Inner shells are part of the central object. They contain systems that relate to the state of the central object only. Outer shells surround the central object and contain peripheral systems. The beauty of a shell is that it can, literally, confine systems that exist as waves or as particles when measured (and thus Schrodinger's equation applies?).

A photon system is a bosonic system. It consists of a central photon object containing a single shell which in turn contains a quantum of energy. The central photon object is surrounded by a single shell containing interacting ELECTRO amd MAGNETIC waves. These  would be observed as E and M particles (my name) if they could be observed.The E and M particles rotate in circles with the centre of the circle at the centre of the photon system. The E particle rotates in the direction of travel of the photon system, and the M particle rotates at right angles (i.e. transversely) to the E particle 

When travelling at the speed of light this photon system behaves like an EM wave. The circular rotation of the E and M waves become sinusoidal E and M waves. The wave length of the EM wave is the diameter of the outer shell.

When interacting with a fermionic system, the photon system is absorbed by the fermionic system. The time taken for this absorption is λ/c where λ is the wave length of the photon system and c is SOL. The energy of the central photon is transferred to the fermionic system and the E and M particles annihilate each other. Note that this energy will likely vary according to changes in the diameter of the outer shell of the photon system (according to E=hc/λ). This may well explain red etc. "shifts", which are postulated in current physics despite, apparently, their breaking the conservation of energy.

Because of the quantum nature of reality the energy transfer process cannot be interrupted. All or nothing of the photon energy must be transferred.

What a shell is made of is unknown. But it may form due to spacetime being modified by the presence of massive particles (see https://einstein.stanford.edu/SPACETIME/spacetime2.html).

[evan_au]

I would love to see the code behind this. Or even a description of what the code does. Given we don't actually know what happened at the time of the Big Bang, I am skeptical that such a simulation could exist.

The references at the bottom of the Wikipedia article will give you more details than you can handle.

Although the physics of gravity is fairly simple (Newton got it almost right), one of the challenges in a simulation like this is that particles which are far apart can use large (simulated) time steps, while those approaching closely need very small time steps. That makes it hard to run on parallel computers, since all the computers have to share information with each other in simulated time.

Despite the existence of compilers that can spread a single piece of code across thousands of CPUs, the need for parallelism does somewhat obscure the code.

See: https://en.wikipedia.org/wiki/Illustris_project

Not sure what kind of a simulation this was, given we don't actually know what happens inside a super nova

It was the first successful simulation of a supernova, with a full 3D simulation of the star on a large supercomputer.
Previous attempts had used a 1D or 2D simulation of a star, modeling composition, temperature and pressure with depth, as well as the nuclear effects expected under these conditions. They could only get enough computer time to simulate about 1 second of the star's last moments. As the video said, all these ended with a black hole, not a supernova.

That's very not surprising, as astronomers estimate that there should be around 4-8 times as many supernova in our galaxy as we actually see; one theory is that the star might get swallowed by a black hole at its center before it can explode as a supernova.

This supernova simulation needed to include the 3-dimensional nature of the star and magnetic/conductivity effects. They also simulated a whole 3 minutes of the stars last moments. Even then, they needed to tweak some parameters to get the simulated star to explode. A 3D model of this nature takes an enormous computer.

See: https://www.space.com/30133-supernova-3d-star-explosion-simulation.html

...and it looks like it was published in 2015 - I thought I heard about it much more recently than that!

[mxplxxx (OP)]

The references at the bottom of the Wikipedia article will give you more details than you can handle.

Except the one I really need, which is a look at the code! As well, much of an attempt to explain the workings of the simulation is incomprehensible, even to experienced physicists I suspect - let alone a lay person. Both these facts make me highly suspicious that the simulation is a furphy.

From Wikipedia.

A furphy is Australian slang for an erroneous or improbable story that is claimed to be factual. Furphies are supposedly 'heard' from reputable sources, sometimes secondhand or thirdhand, and widely believed until discounted.

Ditto to the SuperNova simulation which was apparently fudged anyway due to their code not producing a SuperNova.

[mxplxxx (OP)]

That makes it hard to run on parallel computers, since all the computers have to share information with each other in simulated time.

Impossible not hard, I would have thought. A quantum computer may be the shot, but these appear to be a long way off if at all possible. I doubt very much whether real simulations are being run. A real simulation will start with particles and model how aggregations of them evolve over time. But, hey, isn't this sort of simulation how the universe itself operates? i.e. a processor per particle.We probably need to start at some level of abstraction that arises from the a theory of the way particle interactions occur at  a basic level. But I have not come across such a theory.

[jeffreyH]

I tell you what I believe is a 'Furfy', a self professed 'rock star' coder with an over inflated ego trying to smear the reputations of professional scientists. Much like any other grifter.

[mxplxxx (OP)]

I tell you what I believe is a 'Furfy', a self professed 'rock star' coder with an over inflated ego trying to smear the reputations of professional scientists. Much like any other grifter.

This is incorrect and probably libelous.

[evan_au]

A furphy is Australian slang for an erroneous or improbable story

A Furphy (Trademark) was a real thing in Australia - a water tank used for agriculture, firefighting, and providing water to troops in World War 1.

Furphy_water_Cart.jpg (110.14 kB . 800x600 - viewed 3786 times)

Furphy_water_Cart_Caption.jpg (429.48 kB . 1024x1365 - viewed 3714 times)
Unfortunately the chain covers a crucial part of the story, but during WW1, the driver taking the water cart around to the troops was the carrier of the latest rumours*. This is the origin of "Furphy" in Australian slang. Since you are in Australia, you can see a real Furphy at the Museum of Fire in Penrith (and other museums around the country).

But for the purpose of this discussion, I can assure you that:
- Many physicists know how to write computer software
- Even more have competent programmers they can call on for particular tasks
- Software is extensively used in all branches of science
- When I went to university, we had to learn how to program in FORTRAN (FORmula TRANslation) in first year. At that time, FORTRAN had been the main language for scientific programming for many years
- Later language options at the time included C, LISP, APL, COBOL, etc.

A joke doing the rounds when I was at university:
Question: "What style of programming language will be used for scientific programming in the year 2000?".
Answer: "I have no idea what style of programming it will be - but I do know what it will be called - FORTRAN!"
...and the joke turned out to be true - large scientific simulations are still written in FORTRAN, but with far more structure than earlier versions, and with options to assist running on large parallel computers.
So if you want to understand physics simulations, you had better go back to the future, and learn FORTRAN!

Listen, for example, to the discussion of software used for simulating nuclear fusion experiments (a 100+ dimensional optimisation problem). Much of this podcast is about physics simulations, but listen for 10 minutes from:
https://omegataupodcast.net/312-the-wendelstein-7-x-fusion-experiment/#t=1:40:00

So the only furphy here is the suggestion that physicists don't use simulations.

*Incidentally, "Scuttlebutt" has a similar origin, but in a naval context.

[mxplxxx (OP)]

So the only furphy here is the suggestion that physicists don't use simulations.

Where did I say that?  What I am saying is that physics simulations are hard to find. Even harder to find are ones that come with lucid descriptions of the software. And of the few I found, none supplied code.

The reason Fortran is used for modelling physics phenomena is that it it the best language for implementing mathematical formula. The reason I say modelling rather than simulating is that most simulations I am aware of are based on UML StateCharts which is a kind of software framework especially designed to implement software simulations. I am an expert in these. Such simulations are based on the "how" of physics rather than mathematical predictions.  (see http://ce.u-sys.org/Veranstaltungen/Simulation%20and%20Modeling%201/%C3%9Cbung%2002/SM_E2_RTUMLAnyLogic.pdf)

Thx for the information on furphies. President Trump's false news is in effect furphies. It is wise these days to question anything that comes without evidence of its validity. There is grant money to be made in convincing furphies. How about the Nature article that talks about particles travelling at 40 time the speed of light with no evidence of the validity of the statement. If these guys aren't angling for grant money, I'll be very surprised.

You say "Many physicists know how to write computer software" Fair enuff. I wonder how many of these know how to program simulations using UML Statecharts?

Actually I have my own simulation framework that I hope to foist on the computer profession soon. It is called 3dAbstractions and is based on Hierarchical Finite State Machines theory. 3d as in D for Display, D for Data and D for Datastore. I am a great fan of the Holographic Universe theory (see https://www.southampton.ac.uk/news/2017/01/holographic-universe.page). I have applied the principles of the theory to my software. Data is equivalent to 2d data at the edge of the universe. Display is a 3d projection of the Data onto
a  computer screen. Datastore is permanent memory (which  would exists as 4d spacetime in Einstein's universe).

[jeffreyH]

And I quote.
If you are trusting code monkeys to write your programs, you will be skating on very thin ice:). For something like a physics simulation, either do it yourself if you are good enough or assign it to a rock-star Software Developer with a physics bent (like me:)).
End quote.

That looks like the statement of a self professed rock star coder. It also looks like the words of someone with an over inflated ego.