Should I force an 130 mm hub into my old vintage alu frame I have a classic vitus 979 aluminium road frame where the rear dropout width is 126 mm. Most of the things I hear is that you should not use force on an alu frame and try to fit in an 130 mm hub in there, like you could on a vintage steel frame, but some say that the vitus 979 frame has so much spring in it.

I'm not sure what to do, I want to have modern wheels on it, should I try to force it?
First, try to find a modern wheel that's the right size. They are still made and you can get very shiny ones that will match the bike very nicely. Or get a 120mm fixie hub and add 3mm of spacers each side.

If you must use a modern wheel, try to shrink your hub. Many hubs have washers between the locknuts and cones, or other spacers. If you can remove even a couple of washers to bring the hub width down you're better off. Ideally keep the hub symmetric, but a millimetre out is not the end of the world. Note that you'll need cone spanners and a little skill to adjust things after you do this. With a modern sealed bearing hub it's easier, but with a classic bike like that I suspect you're not putting new wheels in it.

Finally, spreading the frame 4mm should be fine. It'll make getting the rear wheel in harder. With aluminium, do not try to cold set the frame. Once the aluminium yields a lot of the strength is gone and you've basically destroyed the frame.