Science is a way to ask questions of external reality, not a set of fixed ideas about it:
“Science is not about building a body of known ‘facts’. It is a method for asking awkward questions and subjecting them to a reality-check, thus avoiding the human tendency to believe whatever makes us feel good.” (Pratchett et al., 1999)
Science doesn’t tell us what the physical world is but how to study it, by limiting the questions we ask to those that observation can check. Hence, theories about a multiverse (Tegmark, 1997), or saving and restoring reality(Schmidhuber, 1997), or that virtual realities nest (Bostrom, 2002), are speculations beyond the scope of science because they can’t be tested by observation. In contrast, that the physical world is virtual is a statement about this world that science can test by observation, as will be shown.
Science works by contrasting mutually exclusive theories with respect to the observed evidence and rejecting the least likely, so theories must be falsifiable. Virtualism is falsifiable because any incomputable physics would disprove it:
“… the hypothesis that our universe is a program running on a digital computer in another universe generates empirical predictions, and is therefore falsifiable” (McCabe, 2005) p1
If the physical world wasn’t computable, it couldn’t be virtual, but it is. Physical realism is falsifiable too, although its falsifications are called unsolved mysteries (Aspect et al., 1982).
Quantum theory is a science because it is testable by observation, even though quantum waves aren’t physical. Being able to observe what a theory describes isn’t a demand of science, and never has been:
“Atomism began life as a philosophical idea that would fail virtually every contemporary test of what should be regarded as ‘scientific’; yet, eventually, it became the cornerstone of physical science.”(Barrow, 2007) p3
Current physics has unobservable quarks, invisible fields, and virtual particles, so it can hardly make visibility a demand of science. There is no need, as science only requires a theory to predict observables, not to be about them. For example, that our universe began long ago is accepted by science based on the evidence, even though we can never observe it. If science can decide that our universe began based on the evidence, it can decide if it is virtual or not. Quantum realism doesn’t contradict science but engages its spirit of enquiry.