which is the correct way of doing it. Allocating and deallocating, especially larger chunks of memory, requires you to interact with the operating system.
This should off course be avoided in tight loops.

I've been writing a scientific simulation in Fortran for half a year now. I usually like to write in some combination of C and Python.

While Fortran does make the life of a compiler writer easier, I think C benefits from being a small and very popular language.
C compilers are just more advanced, which gives it the speed advantage. But the speed difference for most purposes is negligible.
Choosing the right algorithm and approximations is a much more important concern (factors of 10-100-1000 vs. 1.1-1.2-1.3).
Dynamic memory management is not much different from C.

In my experience, Fortran is extremely useful for expressing linear algebra, which is heavily used in quantum mechanics.
At least it is much much better than C. So in terms of programmer efficiency in scientific calculations, I think Fortran beats C by quite a margin.

Fortran sucks at pretty much anything else though. For example, I think it's a lot easier to have a config module (e.g. class) to manage simulation parameters and recompile the whole application every time you change settings than it is to use an actual configuration file.

The next time I write a scientific application, I think I will have Python handle the logistics (parallelization, files, user input, etc.) and let Fortran do the (heavy) computations.

The only difference between boys and men is the price of their toys.

I never stopped having toys. My current favourite toy is a femtosecond laser system ;-)

I didn't but one of my friends did. He is some 15 years older than me, and was working as an electrician. On top of that, he is dyslexic.
We both study physics now. He's soon finished with his masters degree. I started right after high school, and I'm currently doing a phd.

I am a phd student in physics. I started the same year as an electrician about your age. I'm not sure if he quit his job or went down in time.
But he manages very well.

He's only a few years behind me, and about to finish his masters degree. He's even dyslexic, so I'm quite impressed by him.

My GPA is way more than 4. It probably has something to do with the fact that in Denmark, the scale goes from -3 to 12.

So now what the bad guys have to to after tampering with audio recordings is to subtract the hum of the mains and add the hum at a different time. ?

Wikipedia has an answer, but I think the above is just meant to give the layman some rough understanding of what's going on.

Beware that it is extremely difficult to measure these kinds of distances exactly. The figure may be a few orders of magnitude wrong, so whether you take into account the expanding universe or not may not be that important...
Cosmologists measure everything in gigaparsec. 7b light years is only 0.3 GPc so it may not be that important.