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Question: Why doesn't the Minkowski metric appear in proper form in spherical coordinates on initialization?

Question:Why doesn't the Minkowski metric appear in proper form in spherical coordinates on initialization?

Hullzie16 398 Maple 2025
minkowski spherical-coordinates physics
5 hours ago
0

I want the Minkowski metric in spherical coordinates, so I do the following:

> 

restart;
> 

with(Physics):
> 

Setup(coordinatesystems=spherical,signature=`-+++`);

`Systems of spacetime coordinates are:`*{X = (t, r, theta, phi)}

  

[coordinatesystems = {X}, signature = `- + + +`]

 (1)
> 

g_[lineelement]

-Physics:-d_(t)^2+Physics:-d_(r)^2+Physics:-d_(theta)^2+Physics:-d_(phi)^2

 (2)
> 

 

Which is not correct, it should return:

-d_(t)^2 + d_(r)^2 + r^2*d_(theta)^2 + r^2*sin(theta)^2*d_(phi)^2

Any ideas why it is giving the wrong answer? I usually just define my metric manually, but I was curious why this is occuring. I also noticed something else strange: after running the worksheet, if I go back to the setup line and execute, it will return the correct expression! But if I execute restart and then Setup again, wrong answer. 

Any thoughts would be appreciated, thanks! 
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