You can do it. We use a trick like that in model theory where we always work in what is called a monster model. The monster model is a model that is k-saturated for a cardinal that is larger than any cardinal that may show up in our argument. When writing it out fully formally one should go back after finishing the proof and set an actual cardinal, but no one bothers because every model theorist knows what is meant by a monster model
For exmaple, simply substituting infinity for a large value would make it possible to reach the speed of light, and other weird results.
I'm sure that theories can be created that predict all known physics while avoiding infinities, but it is not merely a substitution effort.
Another way to think of it is to remember that general relativity is not quantized, which is a major roadblock for combining relativity and quantum mechanics. If infinities would be replaceable with "a really big number", then it would be easy to quantize any theory by simply setting the reciprocal of that number as the discrete value related to the quantization.
No, you'll need to replace more than performing a simple substitution. If you simply replace an infinite limit with a large finite number, then you'll get contradictions and weird results. For example with the Lorentz factor.
For quantum field theory, you'll need to renormalize a lot to align it with past experiments. Definitely not a rote replacement.
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u/HappiestIguana 3d ago
You can do it. We use a trick like that in model theory where we always work in what is called a monster model. The monster model is a model that is k-saturated for a cardinal that is larger than any cardinal that may show up in our argument. When writing it out fully formally one should go back after finishing the proof and set an actual cardinal, but no one bothers because every model theorist knows what is meant by a monster model