I agree with this but I would also take it further. I think that all science is purely the mental activity of humans. What is really happening is that we are probing the nature of our own mind, even in fields like physics (and I say this as a physicist myself). My justification for this is Kantian. We can't get away from the fact that our brain structures reality so that we can understand it, for example by organising things via our notions of space and time. We can't access the "noumena", i.e. the things as they truly are, independent of our perception of them. Therefore the study of physics, or indeed literally any activity, can only ever be transcendental and reflexive, rather than actually reaching out into the "objective world".