I disagree with Mr. Budzynski.

Here is the definition of the term abstract.

adjective

abˈstrakt,ˈabˌstrakt/

existing in thought or as an idea but not having a physical or concrete existence.

synonyms:theoretical, conceptual, notional, intellectual, metaphysical, ideal, philosophical, academic

Before their discovery the theoretical arguments for gravitational waves were compelling. But until they were observed, they were abstract theoretical entities.

If we claim that abstract theoretical entities exist in the physical world before they are definitively observed, then we are on a slippery slope heading toward pseudoscience. In some domains of physics, I think we have already slid into that swamp.