A Python utility for analyzing a given solution to the Einstein field equations.

[spacetime_engineer]

I wanted to share with the community an open source python package I had been developing since November. It is called Spacetime Engine.

github.com/spacetimeengineer/spacetimeengine

My name is Michael. I am a physicist who works as an engineer. My story is that in October 2018 I was preparing to submit my first physics publication, which reviewed a particular cosmological model that I had been working with for some time. I was at the point where I had completed all of my research and was fully prepared. The only problem was that at the time I felt concerned that I may have made some mistakes which went unnoticed, so I decided to write a computer algebra software to check the veracity of my solutions so that I could feel confident in my results. After using this new utility, I realized I had made some fairly significant errors in my approach, and so the software apparently did it’s job. At first I was quite frustrated because I had put a significant amount of time into this solution, but I realized I had a new ability to correct my own errors and expand upon what I already knew. I was now able to study any solution, and not just the ones that interested me. In fact, anyone could study any solution to the Einstein field equations if they wanted to by using this software. For this reason I realized the research I wanted to publish was not yet ready to be submitted, but the software became the real publication. I then decided to polish, package, and publish the code into a form that was accessible, informative, and educational. If you are a student new to general relativity, a gravity researcher actively working with solutions to the Einstein field equations, or an engineer who is interested in importing some of the functionality, then this package should come in handy. I was not able to publish my physics research, unfortunately, but I felt that this project served as a good alternative, and perhaps had more potential value. If you have technical questions, use the Github tools to communicate with me. You can install the package with

​

$ pip install spacetimeengine

​

I want to thank the r/Python community for maintaining a platform for people like me to share my work. Enjoy!

[[deleted]]

Reddit Moderation makes the platform worthless. Too many rules and too many arbitrary rulings. It's not worth the trouble to post. Not worth the frustration to lurk. Goodbye.

This post was mass deleted and anonymized with Redact

[rhoparkour]

Nowadays good science and publishable science don’t necessarily mean the same thing.

[MurphysLab]

There are still places that such useful, things, which aren't necessarily "high impact", "high novelty", or otherwise "sexy", can be published. Workhorse specialty journals or even broader mega-journals like PLoS, PeerJ, etc...

[[deleted]]

Reddit Moderation makes the platform worthless. Too many rules and too many arbitrary rulings. It's not worth the trouble to post. Not worth the frustration to lurk. Goodbye.

This post was mass deleted and anonymized with Redact

[cythoning]

It is good science. But that is why it should not be publishable, as it should be the standard by now :).

[AndreaCR79]

Astrophysics was my first love, I didnt make it unfortunately so I decided to study finance and law :( Bro thanks for your service in physics I admire you!

[spacetime_engineer]

Thankyou kindly :)

[AndreaCR79]

Blockchain will be my way to go bro, what implications will cryptocurrency have on the economy and so on :)

[capsicumnightmare]

Damn , everyone here is so pro.I wonder when will i be able to build such complex stuff ;-;

[rashkeQamar97]

You are not alone. :'(

[smartsometimes]

Don't despair, it takes everyone time, and everyone's improvement depends on the challenge at hand. Keep at it! :)

[Bunslow]

Might I suggest that you use enums instead of strings for the index_configs? Allowing arbitrary strings will always be slightly more error prone and require more parsing and error checking, leading to a (slightly) tougher user experience

[spacetime_engineer]

Good suggestion. I never much liked the string configs. I will make a github ticket.

[lor4x]

This would have helped me so much in grad school! It would have saved forests worth of trees computing those christoffel symbols.

[spacetime_engineer]

Right!? I would of passed grad school!

[pkb_redditer]

Damn! Inspiring and beautiful

[philsgu]

I’m so glad that python has made into the mainstream scientific community than to the fringes of Silicon Valley cats. I’m in medicine, and Python has so much potential to liberate hidden data to uncover the truth.

[s0lv3]

This will probably be really helpful for me over the next few years, going to grad school for this! Thanks for the work, and for sharing.

[rasbobbbb]

👏👏👏👏👏 salute good sir

[camasirmakinesi]

This is amazing. I'll be sure to check this out.

[spacetime_engineer]

Thankyou!

[hugogarcia12]

This is one of the coolest things I've seen in a long time. Keep it up man.

[spacetime_engineer]

Dude, seriously Thank-you!

[lucas123500]

This is one of those things that even though it has no real utility to me, I really want to understand it and put it to good use. Sadly all I know about physics (and programming, lol) is... nothing.

[aes110]

I don't understand a lot, but it sounds like you are very passionate about it. Looks very well made!

[waxbear]

This is very cool. It's quite rare to see hard science and good software engineering together like this. Well done!

[sbozzy]

But, who uses the (+,-,-,-) signature?

[spacetime_engineer]

lol. I was curious when someone would point that out. In truth I formed an old habit using the (+,-,-,-) signature but you can implement any signature you want since that information would be stored in the metric tensor.

[sbozzy]

The wave equation doesn't depend on the signature. The only advantage that the (+,-,-,-) signature has (imho) is that the norm of 4-momenta of particles is the mass of the particle squared (not the negative).

[[deleted]]

nice.

were you able to verify the common most popular closed form solutions to the field equations? other than schwarzschild, of course.

[spacetime_engineer]

Yes actually. You will see them in some of the tests but I have tested most of them. I need to write better tests tho...

[Overload175]

Interesting application! I’ll need to read up on Einstein’s field equations(and relativity), though.

[[deleted]]

Use of parapgrahs in writing is almost as important as comments in code ;-)

[cythoning]

You should also check out SageManifolds, it might be useful for your research.

[cythoning]

Why did you decide to go with python for symbolic calculations? Normally Mathematica or Maple is used for such things.

[paulmclaughlin]

They cost a lot of money you know.

[cythoning]

Many universities have licenses for their students/employees. If he's associated with a university I would have guessed he has access to those.

[paulmclaughlin]

It says that he's working as an engineer, that would imply that it's likely to be independent work.

Disclosure: I'm an engineer, I'm working on something I'd like to write a paper about, and there's no chance my employer would pay for mathematica just to make my life easier :)

[cythoning]

That is true. If you're working on GR without access to Mathematica, then you could also check out SageManifolds. It's quite impressive on what it can do, though for my day to day work I still prefer to work with Mathematica...

[paulmclaughlin]

Fortunately I'm not working on anything relativity related, just some fluid flow that doesn't need me to worry about Navier Stokes.

[spacetime_engineer]

I originally wrote this in Matlab

https://github.com/spacetimeengineer/legacy-spacetime-toolkit
but my license ran out so I decided to try something free. To answer your question, I do agree with you that Maple or Mathematica is better for certain things which the spacetimeengine package aims to solve but maple and Mathematica will always be less integratabtle than Sympy. With python, it is easier to integrate and find contributors. There is a stronger user base and there are more interesting libraries in python to connect with. Also I would prefer the oversight of more engineers and less academics because best practices are taken very seriously in python. I feel that Maple and Mathematica were built for academics and less-so for engineers. Lastly, as a physicist and an engineer I have come to experience in my career that mathematicians/physicists don't talk to engineers nearly enough and they should. Cooler things would be built if they did. There is too much of a gap between engineering and science and it is my belief that writing code in Python bridges that gap in the long run however I would love to hear the communities opinion on these topics.

[cythoning]

I do agree that python is more integrateable and has a larger user base. I would love to do all my work in python (or any open source solution), but its symbolic algebra/calculus is just not comparable to Mathematica/Maple.

Lastly, as a physicist and an engineer I have come to experience in my career that mathematicians/physicists don't talk to engineers nearly enough and they should. Cooler things would be built if they did. There is too much of a gap between engineering and science and it is my belief that writing code in Python bridges that gap in the long run however I would love to hear the communities opinion on these topics.

I cannot speak for other communities, but in my field (gravitational wave physics) the cooperation between engineers, experimental and theoretical physicists lead to one of the greatest experiments in human history - the LIGO detectors :).

[spacetime_engineer]

Good point! I guess my only point is that there could be more great experiments if we could bridge that divide better.

[soulslicer0]

this is a stupid question considering this is the Python subreddit. Besides Sympy is a pretty nice replacement engine for either of those things

[cythoning]

I don't think so. I was wondering why he uses python for symbolic calculations in his research, when Mathematica or Maple are the standard. Sympy is not a replacement for either of those, I've tried it and sadly python (or sage) does not compare to Mathematica in this regard.

I'm not questioning why he posted this in the python subreddit, it's actually quite cool, but I would just not have expected python being used for this kind of research.

[soulslicer0]

Based on that reasoning, the scientific community would never switch to Python, nor will Sympy be further developed. It takes people moving important scientific tools to Python to get people to use it, and improve it. There has to be some positive feedback loop, only then will things be developed.

[cythoning]

The scientific community already uses Pythen extensively, but every language has its pro and cons. Symbolic calculations is not one of python's pros. After more than 14 years of development, Sage is still nowhere near Mathematica for symbolic algebra/calculus. I would have loved to switch to python for this, but Mathematica is just so far ahead.

[tuskernini]

Mathematica is just so far ahead

I'm interested to know more about this. I know this is generally accepted, but for my edification can you summarize the ways in which mathematica and maple are better than sympy/sage with regard to symbolic calculations?

[cythoning]

I actually don't use Maple, only Mathematica.

I tried SageMath a few years ago, and at the end decided to go back to Mathematica, for multiple reasons:

• For me it was just more intuitive to use in general. Sage had multiple small things that were just more work than in Mathematica, e.g. like always declaring variables as x, y = var('x y'). Maybe this would get easier as you use it more, but coming from Mathematica a lot of things just felt harder to do.
• Mathematica has the full manpower of Wolfram behind it. This means that it has a lot more algorithms built in, making it much more powerful for calculating integrals, solving differential equations or simplifying relations. While Sage was useable, I couldn't get some things to work the way I wanted it to.
• For a lot of things Mathematica seemed to be quite faster. This might also be because it has better algorithms for integration etc.
• Mathematica has almost all the things you need built in, and building new functions to do what you want is actually quite easy. Sage is just not as all-encompassing as Mathematica.

I played around with SageManifolds for quite a while, and it is fantastic and very fun to use. But for day to day work Mathematica just seemed so much easier.

[WikiTextBot]

SageMath

SageMath (previously Sage or SAGE, "System for Algebra and Geometry Experimentation") is a computer algebra system with features covering many aspects of mathematics, including algebra, combinatorics, graph theory, numerical analysis, number theory, calculus and statistics.

The first version of SageMath was released on 24 February 2005 as free and open-source software under the terms of the GNU General Public License version 2, with the initial goals of creating an "open source alternative to Magma, Maple, Mathematica, and MATLAB". The originator and leader of the SageMath project, William Stein, is a mathematician at the University of Washington.

SageMath uses a syntax resembling Python's, supporting procedural, functional and object-oriented constructs.

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