Are we seeing useless physics today?
By useless physics I refer to for example the study of multiverse(s): it is useless because there is no use for it to mankind - except that there are physicists who employ mathematics to propound it, but no one with intelligence can see any use it has for mankind, like is multiverse(s) of any use in producing clean energy?
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There is a story, possibly apocryphal, of Faraday demonstrating an electromagnetic induction experiment at the Royal Institution in London. He was asked, what use is it? According to one version, he replied, "What use is a baby? It grows up." In another version, it was a politician who asked, "What use is it?" and Faraday replied, "Soon you will be able to tax it." In another example, Hertz discovered radio waves and said of his discovery that it was of no use whatsoever.
The point is, we don't always know what some speculative piece of physics will eventually turn into. As to the idea of a multiverse, some have conjectured that we may be able to breach the link between universes with experiments of sufficiently high energy. Maybe we will, and maybe if we do it will open up some important new discoveries. Until then, it is just a 'useless' conjecture.
To answer the title of your post, physics can be manipulated, similar to other sciences, philosophy and religion. A sensational example is offered by one Dr. David Grimes, a physicist who claims he has created a formula that can magically tell us if a particular conspiracy theory is valid.
The article I linked to below appears in PLOS ONE. And if you don't think it's an authentic scientific journal, note that it's "peer reviewed."
On the Viability of Conspiratorial Beliefs -- David Grimes, PLOS ONE, January 26, 2016
However, the example you cited - the multiverse - is a little different. I'm not clear how it might be used for propaganda purposes. It sounds like a perfectly credible, if offbeat, theory.
It might qualify as "useless" in the sense that it's hard to imagine how we could realize any practical benefits from such a theory in the near future. If we could discover another universe with another planet exactly like Earth - but unpopulated and unpolluted - then somehow transport seven billion people from Earth to its distant cousin, then all this multiverse research might have practical significance. Of course, that's never going to happen.
In the meantime, I don't understand the problem with scientists speculating, theorizing and expounding on black holes, wormholes and multiverses. Isn't that what science is all about - asking questions and pushing the envelope of the known?
As others asked in the comments, why does a particular scientific inquiry have to be "useful"?
Much of the time after a paradigm is very full is spent attempting to reframe the overgrown system it in simpler terms.
The long death cycle of Ptolemaic Astronomy, as described by Kuhn, was all about describing the same things either more closely, or more simply. And the push toward simplicity eventually moved people like Kepler to consider astronomy that admitted conic sections. The conic sections fit perfectly with a quadratic theory of gravity, and we could imagine a single set of rules that described both celestial mechanics and ordinary ballistics, setting the groundwork for Galileo, and his theories of uniform motion and acceleration.
So all of that thrashing about trying to simplify, eventually bore fruit, even though all of it was perfectly pointless and never accomplished anything itself. It shifted the focus around enough to free up the paradigm to shift. Loss of precision and minimalism came to be seen as an acceptable price to pay for a less cluttered model.
Physics appeared to be headed into such a state right before quantum dynamics was discovered. So it was spared this experience once. But it is now largely in the same place. And we have seen other sciences come through such spaces and grown on their account.
The alternative versions involve different extraneous furniture, and then we can see whether those things correspond to reality, or not, if we can't tell. If they do, we are actually discovering things that may eventually be useful. But if we can't tell, that may be even better, because we can describe our physics in simpler way, without losing anything. String Theory will never net anything new. By design, it can't. But it may simplify physics in the long run. We may never need to know all the ways our space might have been, but by discovering the set of parameters, we might be able to describe what actually is in a more general and equally meaningful way that will be easier to preserve and pass on.
There is also a distinct possibility that physics will be spared the inward spiral once again. The stuff currently arising out of the integration of physics and information theory, and the problems the two have agreeing on what happens at black holes could easily net another branch of physics like quantum mechanics, and we can move from cleanup and reframing operations into a whole new realm.
At first blush, quantum mechanics seems useless, as it describes mostly what we cannot do, or can't understand. It arose out of a sort of desperate mopping-up approach to the last unsolved problems of classical physics. Planck, its originator did not see it as a realistic approach to anything, despite the fact it solve the problem of the 'ultraviolet catastrophe' in black-body radiation. But it was. It took over. And it has given us the nuclear age and things like semiconductors.
Information physics could be a crazy obsessive little corner between thermodynamics and relativity, or the new quantum mechanics.
