I think we can acknowledge that experiments, and the experimental method, have been of great benefit to humanity. Most of us have a basic understanding of what experiments comprise. Experiments typically address things; there is a physical subject matter (however complicated or indefinite) involved in the process. There is a problem to be resolved, or a question to be answered through the experiment. There is a hypothesis, and its validity or invalidity is established, wholly or partly, through the experiment. Certain steps are taken, certain results are observed.
"Thought experiments" as I understand them are imaginary exercises, engaged in purportedly to investigate things which are not imaginary. I'm not sure where the phrase comes from or when it first came into use. It smacks of jargon, though, so I suspect we began to use it in the late 19th century or sometime in the 20th century. This would seem to make sense as it was in that period that the non-scientific disciplines, and those who were not scientists, began to emulate the scientific or experimental method. That method had been so successful that those in the humanities and in professions such as the law sought to share in that success, or at least appear to have the same claim to veracity.
I find the phrase puzzling, though. Imaginary exercises and devices seem quite unrelated to experiments and the experimental method. I don't see how an imaginary device can be considered remotely similar to an experiment, as commonly understood. "Thought experiments" seems almost an oxymoron.
It's clear enough that thoughts always accompany experiments. But the subject matter of experiments are not imaginary, and in order to accomplish an experiment certain acts are required, acts which take place in "real life." The use of the phrase, and the claim that one is engaged in a "thought experiment" therefore seem to be in the nature of a pretense, i.e. it is pretentious to claim one is carrying out a "thought experiment." One is pretending to apply the experimental or scientific methods, to be scientific, to be a scientist. However, what is actually taking place is an excursion into "Imagination Land" (not the one in South Park, though). There is nothing wrong with taking such a trip; we do so often, and such trips can be beneficial. But it would seem less pretentious, and certainly more honest, to simply say that we are considering in our imaginations something which is not the case, in the effort to learn something regarding what is the case.
Clearly those who perform actual experiments use their imaginations and speculate. They may wonder, for example, whether a certain act or element will resolve a problem, or a certain explanation will adequately address a question. However, they then proceed to do something. They do not merely imagine and speculate; they do more than think. They subject their speculation to the test of the experiment, and determine thereby whether the speculation usefully meets the test.
There is no experiment available to test "thought experiments" however. The imagining does not end, unless it is abandoned. It may be abandoned for a reason; for example, those doing the imagining may come to the conclusion that the thought experiment is so hypothetical, so remote from the real, so convoluted as to be silly or incredible. But the hypothesis being bandied about in "Imagination Land" cannot be tested in the sense that a hypothesis can be tested, or a course of action or judgment regarding real life can be tested by application to real life problems and questions.
Some of the less incredible "thought experiments" may be useful in the sense that they get us thinking. But I think it is foolish to believe they are of any more than minimal use in understanding the universe, ourselves or others. The best way to address and resolve the problems we encounter in life is by addressing them in real life, not exclusively in the imagination.
There is a limit to the extent imagining things can effect the way in which we react to things that actually happen. For one thing, as a general rule, our imaginations are lacking. We usually find a way to leave something "real" out of our imaginary scenarios; they are not compelling because they are so clearly unreal. For another, imaginary problems and situations simply do not induce the kind of thinking and acting we do when we encounter actual problems. Particularly in emergency situations we do things unthinkingly, and no amount of philosophical imaginary training will provide us with any guidance.
We should not put much faith in, or grant much credence to the "results" of, "thought experiments." They have no outcome, and where there is no outcome nothing is achieved.